Prepared in cooperation with Kenai Fjords National Park

Kittlitz’s and Marbled Murrelets in Kenai Fjords 

National Park, South-Central Alaska: At-Sea Distribution, 

Abundance, and Foraging Habitat, 2006–08

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2010–1181
Cover: Two species of Brachyramphus murrelet in alternate plumage; Marbled 

murrelet (left) and Kittlitz’s murrelet (right). Photographs by Mayumi Arimitsu.
Kittlitz’s and Marbled Murrelets in Kenai Fjords 

National Park, South-Central Alaska: At-Sea 

Distribution, Abundance, and Foraging Habitat, 

2006–08 

By M.L. Arimitsu, J.F. Piatt, M.D. Romano, E.N. Madison, and J.S. Conaway 

Prepared in cooperation with Kenai Fjords National Park 

Open-File Report 2010-1181 

U.S. Department of the Interior 

U.S. Geological Survey 
U.S. Department of the Interior 

KEN SALAZAR, Secretary 

U.S. Geological Survey 

Marcia K. McNutt, Director 

U.S. Geological Survey, Reston, Virginia: 2010 

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Suggested citation: 

Arimitsu, M.L., Piatt, J.F., Romano, M.D., Madison, E.N., and Conaway, J.S., 2010, Kittlitz’s and Marbled 

Murrelets in Kenai Fjords National Park, south-central Alaska: At-sea distribution, abundance, and foraging 

habitat, 2006–08: U.S. Geological Survey Open-File Report 2010-1181, 68 p. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement 

by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual copyright 

owners to reproduce any copyrighted material contained within this report. 
iii 

Contents 

Abstract ............................................................................................................................................................1

Introduction.......................................................................................................................................................2

Methods............................................................................................................................................................3

At-Sea Surveys.............................................................................................................................................4

Productivity Surveys .....................................................................................................................................5

Telemetry......................................................................................................................................................5

Marine Habitat...............................................................................................................................................6

Oceanography...........................................................................................................................................6

Tidal Current Velocity ................................................................................................................................7

Zooplankton ..............................................................................................................................................7

Hydroacoustics..........................................................................................................................................8

Nearshore Fish..........................................................................................................................................8

Data Analysis................................................................................................................................................9

Results............................................................................................................................................................12

Population, Distribution, and Abundance ....................................................................................................12

Kittlitz’s Murrelets ....................................................................................................................................12

Marbled Murrelets ...................................................................................................................................12

Brachyramphus Murrelets .......................................................................................................................13

Density........................................................................................................................................................13

Productivity .................................................................................................................................................14

Observations of Radio-Marked Kittlitz’s Murrelets ......................................................................................14

Marine Habitat.............................................................................................................................................15

Oceanography.........................................................................................................................................15

Prey Availability.......................................................................................................................................17

Habitat Model ..........................................................................................................................................18

Discussion ......................................................................................................................................................18

Survey Design.............................................................................................................................................19

Population and Distribution .........................................................................................................................20

Telemetry....................................................................................................................................................21

Productivity .................................................................................................................................................21

Habitat ........................................................................................................................................................22

Oceanography.........................................................................................................................................22

Prey Availability.......................................................................................................................................23

Acknowledgments ..........................................................................................................................................25

References Cited............................................................................................................................................26

Appendix 1. Total Count of All Birds and Marine Mammals Observed on Early Season 

Surveys, Kenai Fjords, Alaska, 2006–08 ........................................................................................................59

Appendix 2. Total Count of All Birds and Marine Mammals Observed on Mid-Season Surveys, 

 Kenai Fjords, Alaska, 2006–08......................................................................................................................61

Appendix 3. Total Count of Birds and Marine Mammals Observed on Late-Season Surveys, 

Kenai Fjords, Alaska, 2006–08.......................................................................................................................63

Appendix 4. Catch Per Unit Effort (CPUE, # m-3) and Frequency of Occurrence (FO) of 

Small Zooplankton at Stations Sampled with a Ring Net, Kenai Fjords, Alaska, 2007 .................................65

Appendix 5. Catch Per Unit Effort (CPUE, # m-3) and Frequency of Occurrence (FO) of 

Small Zooplankton at Stations Sampled with a Ring Net, Kenai Fjords, Alaska, 2008 ...................................67

 
iv 

Figures 

Figure 1. Map showing Kenai Fjords study area showing place names used in this report ...........................30

Figure 2. Map showing marine bird transect locations in Kenai Fjords National Park, Alaska, 

summers 2006–08..........................................................................................................................................31

Figure 3. Map showing fledgling survey lines in Aialik Bay and Northwestern Lagoon, Alaska, 2007 ...........32

Figure 4. Map showing approximate area (blue) covered by boat-based and aerial relocation surveys for 

radio-marked Kittlitz’s murrelets in the lower Kenai Peninsula area, May 10–July 1, 2006 ............................33

Figure 5. Map showing beach seine (triangles), oceanography stations (squares), and large Isaacs-Kidd 

Midwater Trawl (IKMT, red circles) stations sampled in Kenai Fjords, Alaska................................................34

Figure 6. Map showing large Isaacs-Kidd midwater trawl locations (red circles and black crosses), and 

euphausiid density (#/m3) during sampling, Kenai Fjords, Alaska, June 29–July 3, 2007...............................35

Figure 7. Map showing strata used to generate population estimates for Kittlitz’s and marbled murrelets, 

Kenai Fjords National Park, Alaska, 2006–08 ................................................................................................36

Figure 8. Maps showing Kittlitz’s murrelet distribution during mid-season coastwide surveys, 

Kenai Fjords, Alaska.......................................................................................................................................37

Figure 9. Maps showing Marbled murrelet distribution during mid-season coastwide surveys, 

Kenai Fjords, Alaska.......................................................................................................................................38

Figure 10. Maps showing Kittlitz’s murrelet (KIMU) and marbled murrelet (MAMU) distribution, 

including adult and juvenile records, during fledging period surveys in Northwestern Fjord and 

Aialik Bay, Kenai Fjords, Alaska .....................................................................................................................39

Figure 11. Maps showing location of radio-marked Kittlitz’s murrelets (circles) tracked by boat-based 

and aerial telemetry searches, and capture locations (squares), Kenai Fjords, Alaska, 2006 ........................40

Figure 12. Graphs showing temperature (color) and salinity (line) vertical contours relative to 

bottom depth (m, x-axis) and glacier distance (y-axis) in Northwestern Fjord (two left panels) and 

Aialik Bay (two right panels), Alaska...............................................................................................................41

Figure 13. Chlorophyll a vertical contours relative to depth (m, y-axis), and distance to tidewater 

glacier (km, x-axis) in Kenai Fjords National Park, Alaska..............................................................................42

Figure 14. Water clarity vertical contours (beam transmission, %) relative to depth (m, y-axis) 

and distance to tidewater glaciers (km, x-axis), Kenai Fjords National Park, Alaska ......................................43

Figure 15. Graphs showing monthly average (SD) dissolved inorganic nitrogen (DIN, μM), nitrogen 

to phosphate ratio (N:P), and silicic acid (SiOH4, μM) values in Aialik Bay and Northwestern Fjord, 

Alaska, 2008...................................................................................................................................................44

Figure 16. Graph showing backscatter vertical profile (color, decibels, dB) measured by an acoustic 

Doppler current profiler and salinity data measured at the front of Aialik Glacier, Alaska, 

August 14, 2007 .............................................................................................................................................45

Figure 17. Graphs showing proportion of Isaacs-Kidd midwater trawl catches that were comprised of 

gelatinous zooplankton (GZ) relative to distance to nearest tidewater glacier in Aialik Bay (upper) and 

Northwestern Lagoon (lower), Alaska, 2008...................................................................................................46

Figure 18. Maps showing monthly hydroacoustic backscatter (nautical area scattering coefficient, NASC) 

due to dense forage schools and weaker scattering nekton measured in Kenai Fjords, Alaska, 2008...........47

Figure 19. Graphs showing monthly relationship between acoustic backscatter and transect distance 

to tidewater glaciers in Northwestern Lagoon (top panel) and Aialik Bay (bottom panel), Kenai Fjords 

National Park, Alaska, 2008 ...........................................................................................................................48
v 

Tables 

Table 1. Summary of at-sea survey effort in Kenai Fjords National Park, Alaska, 

during summers of 2006–08 ...........................................................................................................................49

Table 2. Summary of mid-season, coastwide surveys conducted in Kenai Fjords 

National Park, Alaska, during summers of 2006–08.......................................................................................50

Table 3. Population estimates (95%-confidence intervals) and coefficients of variation (%) for 

Brachyramphus murrelets in Kenai Fjords National Park, Alaska, 2006–08...................................................51

Table 4. Proportion (percent) of Brachyramphus murrelets (all behaviors, and flying birds only) 

that were Kittlitz's murrelets (KIMU), marbled murrelets (MAMU), and unidentified Brachyramphus 

Murrelets (UNMU) observed within 100 meters of the vessel during Kenai Fjords surveys, 

Alaska, 2006–08.............................................................................................................................................52

Table 5. Within season density estimates (D, birds/km2), confidence intervals (CI), and coefficients of 

variation (CV, %) for Kittlitz's murrelets (KIMU), marbled murrelets (MAMU) in Kenai Fjords National 

Park, Alaska, 2006–08....................................................................................................................................53

Table 6. Average density (SE) within strata across years for Kittlitz's murrelets (KIMU), marbled murrelets 

(MAMU), and all Brachyramphus murrelets combined (BRMU) during mid-season coastwide surveys in 

Kenai Fjords, Alaska, 2006–08.......................................................................................................................54

Table 7. Kittlitz’s murrelet measurements from May 2006 in Kenai Fjords compared to May 2004 

in Glacier Bay, Alaska.....................................................................................................................................54

Table 8. Nutrient concentrations (μM) sampled in Northwestern Lagoon and Aialik Bay, Alaska, 2008........54

Table 9. Species, size (fork length, mm), and sample size (n) of fishes captured in small and large 

Isaacs-Kidd midwater trawls (IKMT), Kenai Fjords, Alaska, 2007–08.............................................................55

Table 10. Results from 3-way fixed effects permutation-based MANOVA under the null hypothesis 

that there was no difference in Bray Curtis similarity index of Kittlitz's murrelet zooplankton prey 

species in glacial versus distal stations (glacial), Aialik versus Northwestern (fjord), or time 

period (month) ................................................................................................................................................56

Table 11. Species, size (fork length, mm), and sample size (n) of nearshore fishes captured 

with a beach seine in Kenai Fjords, Alaska, 2007–08.....................................................................................57

Table 12. Parameter estimates for best-fit model using generalized linear-mixed models to relate 

Kittlitz’s and marbled murrelet presence/absence (binomial response) to marine habitat variables 

measured in Kenai Fjords National Park, Alaska, July 2008 ..........................................................................58
vi 

Conversion Factors, and Abbreviations, Acronyms, and Symbols 

Conversion Factors 

SI units to Inch-Pound 

Multiply By To obtain 

millimeter (mm) 0.03937 inch (in.) 

kilometer (km) 0.6214 mile (mi) 

meter (m) 3.281 foot (ft) 

square kilometer (km2) 0.3861 square mile (mi2) 

square meter (m2) 10.76 square foot (ft2) 

gram (g) 0.03527 ounce, avoirdupois (oz) 

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s) 

meter per second (m/s) 3.281 foot per second (ft/s) 

Inch-Pound to SI units 

Multiply By To obtain 

square mile (mi2) 259.0 hectare (ha) 

square mile (mi2) 2.590 square kilometer (km2) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: 

°F=(1.8×°C)+32. 
vii 

Abbreviations, Acronyms, and Symbols 

Abbreviations, Acronyms, and Symbols Meaning 

ADCP Acoustic Doppler current profiler 

AIC Akaike’s information criteria 

ANOVA Analysis of variance 

CPUE Catch per unit effort 

CTD Conductivity temperature depth profiler 

dB Decibel 

DIN Dissolved inorganic nitrogen 

ESW effective strip half width 

FL fork lengths 

GIS Geographic information systems 

GLM Generalized linear model 

GLMM Generalized linear mixed effects model 

GPS Global positioning system 

IKMT Isaacs-Kidd mid-water trawl 

μM Micro moles per liter 

N:P Nitrogen to phosphorous ratio 

NASC nautical area scattering coefficient 

PAR Photosynthetically active radiation 
viii 

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Kittlitz’s and Marbled Murrelets in Kenai Fjords 

National Park, South-Central Alaska: At-Sea 

Distribution, Abundance, and Foraging Habitat, 

2006–08 

By M.L. Arimitsu, J.F. Piatt, M.D. Romano, E.N. Madison, and J.S. Conaway 

Abstract 

Kittlitz’s murrelets (Brachyramphus brevirostris) and marbled murrelets (B. marmoratus) 

are small diving seabirds and are of management concern because of population declines in coastal 

Alaska. In 2006–08, we conducted a study in Kenai Fjords National Park, south-central Alaska, to 

estimate the recent population size of Brachyramphus murrelets, to evaluate productivity based on 

juvenile to adult ratios during the fledgling season, and to describe and compare their use of 

marine habitat. We also attempted a telemetry study to examine Kittlitz’s murrelet nesting habitat 

requirements and at-sea movements. We estimated that the Kittlitz’s murrelet population was 671 

± 144 birds, and the marbled murrelet population was 5,855 ± 1,163 birds. Kittlitz’s murrelets 

were limited to the heads of three fjords with tidewater glaciers, whereas marbled murrelets were 

more widely distributed. Population estimates for both species were lower in 2007 than in 2006 

and 2008, possibly because of anomalous oceanographic conditions that may have delayed 

breeding phenology. During late season surveys, we observed few hatch-year marbled murrelets 

and only a single hatch-year Kittlitz’s murrelet over the course of the study. Using radio telemetry, 

we found a likely Kittlitz’s murrelet breeding site on a mountainside bordering one of the fjords. 

We never observed radio-tagged Kittlitz’s murrelets greater than 10 kilometer from their capture 

sites, suggesting that their foraging range during breeding is narrow. We observed differences in 

oceanography between fjords, reflecting differences in sill characteristics and orientation relative 

to oceanic influence. Acoustic biomass, a proxy for zooplankton and small schooling fish, 

generally decreased with distance from glaciers in Northwestern Lagoon, but was more variable in 

Aialik Bay where dense forage fish schools moved into glacial areas late in the summer. Pacific 

herring (Clupea pallasii), capelin (Mallotus villosus) and Pacific sand lance (Ammodytes 

hexapterus) were important forage species for murrelets in Kenai Fjords. Euphausiids also may 

have been an important forage resource for Kittlitz’s murrelets in turbid glacial outflows in 

shallow waters during daytime. Marbled murrelets generally were more tolerant to a wider range 

of foraging habitat conditions although they tended to avoid the ice-covered silty waters close to 

glaciers. In contrast, Kittlitz’s murrelets preferred areas where the influence of tidewater glaciers 

was the greatest and where their distribution was determined largely by prey availability. This 

work highlights an important link between interannual variability in murrelet counts at sea and 

mesoscale oceanographic conditions that influence marine productivity and prey distribution. 

1 
Introduction 

Kittlitz’s and marbled murrelets are non-colonial, diving seabirds of the Alcidae family. 

Like other alcids, Brachyramphus murrelets (hereafter referred to as murrelets) feed on small 

schooling fishes and invertebrates, have a long life span, and delay reproduction until they are 

several years old. The breeding range of the Kittlitz’s murrelet is limited to Alaska and the 

Russian Far East, where they nest inland on talus slopes in glacial alpine or on unvegetated 

mountain slopes in deglaciated areas. Marbled murrelet breeding populations range from central 

California to southern Alaska and the Aleutian Islands, and they mostly nest inland in old-growth 

coniferous forests, usually on mossy tree limbs. In some areas, they nest on the ground. Both 

species are of management concern because of declining populations in core breeding areas 

Kissling and others, 2007; Piatt and others, 2007; Drew and Piatt, 2008; Kuletz and others, 2008; 

U.S. Fish and Wildlife Service, 2008). 

Both species of murrelets co-occur in glacial fjords within coastal Alaska; however, 

marbled murrelets use a wider range of nearshore habitats. Distribution of Kittlitz’s murrelets 

within glacial fjords of south-central and southeast Alaska is highly clumped with apparently 

persistent “hotspots” throughout the summer breeding season (Romano and others, 2004, 2006; 

Kissling and others, 2007). Kittlitz’s murrelets were associated with strong tidal currents (Kissling 

and others, 2007) and preferred glacial-affected, nearshore, and highly turbid areas (Day and 

others, 2003). Marbled murrelets were more closely tied to shoreline habitats, and often associated 

with areas of upwelling near marine sills, mouths of bays, or eddies (Piatt and others, 2007). 

Recent studies suggest breeding success of Kittlitz’s murrelets in some areas of their 

breeding range was low (Day and Nigro, 2004; Kaler and others, 2009). Kaler and others (2009) 

estimated nesting success on an island in the western Aleutians at 0.06 ± 0.03 chicks/pair. This is 

much lower than estimates of 0.32 chicks/pair from direct observations of marbled murrelet nests 

throughout their range (Piatt and others, 2007) or of 0.48 chicks/pair (95% CI: 0.41–0.55) for 

marbled murrelets derived from telemetry studies in British Columbia (Bradley and others, 2004). 

The inaccessibility of murrelet nests adds to the difficulty of assessing reproductive success in 

most areas, and therefore, the ratio of juvenile to adult marbled murrelets observed at sea after 

fledging also has been used to provide an index of productivity (Strong, 1995; Kuletz and Piatt, 

1999; Day and Nigro, 2004; Kuletz and others, 2008). In Kachemak Bay, juvenile marbled 

murrelet nursery areas were documented during late-season surveys (Kuletz and Piatt, 1999; 

Kuletz and others, 2008), although the occurrence and timing of juvenile Kittlitz’s murrelets at sea 

is still poorly known. 

Because of population declines in Kittlitz’s murrelet’s core areas of distribution, the U.S. 

Fish and Wildlife Service (USFWS) designated the seabird as a candidate for listing under the 

Endangered Species Act (69 FR 24875-24904). Marbled murrelets are currently (as of 2010) listed 

as threatened from British Columbia to California, but not in Alaska (McShane and others, 2004; 

Piatt and others, 2007). In Kenai Fjords National Park, surveys conducted between 1976 and 2002 

suggested that the population of Kittlitz’s Murrelets declined by as much as 83 percent during that 

time (Van Pelt and Piatt, 2003). In contrast, Brachyramphus murrelet populations (including a 

large proportion of unidentified murrelets) in adjacent Prince William Sound have declined by 60 

percent in recent decades (Piatt and others, 2007). Similarly, in Kachemak Bay, Brachyramphus 

2 
murrelets declined by 32 percent between 1993 and 2005 (Kuletz and others, 2008). Leading 

hypotheses to explain all or part of the decline include naturally occurring changes in food 

abundance, glacial recession, oil spill mortality, vessel disturbance in foraging areas, and gillnet 

mortality. 

The study area covered the coastal area of Kenai Fjords, Alaska, extending from Callisto 

Head in the east to Gore Point in the west (fig. 1). The outer portion of each fjord is exposed to 

Gulf of Alaska currents, whereas the inner portions are influenced by runoff from glaciers 

extending from the Harding Icefield. For the marine habitat part of this study, two fjords are of 

interest because of resident summer populations of Kittlitz’s murrelets—Aialik Bay and 

Northwestern Lagoon. Each fjord contains a sill, which is a neoglacial terminal moraine shoal at 

the position of the glacier terminus during the Little Ice Age maximum (Wiles and others, 1995). 

Glacial retreat in Aialik Bay occurred around the late 1600s, and ice retreat in Northwestern 

Lagoon began around the late 1800s (Wiles and others, 1995). 

The goal of this study was to examine variability in the at-sea distribution, abundance, and 

habitat use of Kittlitz’s and marbled murrelets during the breeding season (June–August) in the 

nearshore waters adjacent to Kenai Fjords National Park, Alaska. The objectives of the study 

were (1) to determine the population status of Brachyramphus murrelets in Kenai Fjords, (2) to 

attempt to assess productivity based on at-sea surveys, and (3) to contrast the use of different 

marine habitats by the two murrelet species. 

This report summarizes a 3-year study on the distribution and abundance of Kittlitz’s 

murrelets and marbled murrelets in waters adjacent to Kenai Fjords National Park, Alaska. Here, 

we summarize results from systematic, at-sea surveys in the Kenai Fjords during the summers of 

2006–08. In addition, we present results from a pilot radio telemetry effort in 2006, and foraging 

habitat studies in 2007–08. Finally, we discuss factors related to survey design, and interannual 

and within season variability in murrelet counts. 

Methods 

During each year of the study, we conducted surveys in the early, middle, and late periods 

of the breeding season for murrelets (table 1). Data were collected using a combination of boatbased marine bird surveys, oceanographic surveys, nearshore (less than 30 m from shore) and 

offshore (greater than 200 m from shore) fish sampling using beach seines and Isaacs-Kidd midwater trawls (IKMT), hydroacoustic surveys for fish and zooplankton biomass, and measurements 

of tidal current velocity using an acoustic Doppler current profiler (ADCP) near glacial features. 

In 2006, we attempted to characterize Kittlitz’s murrelet foraging habitat by using radio telemetry 

to locate birds at sea. However, only small numbers of Kittlitz’s murrelets were found and 

captured so this effort was not cost effective. The telemetry component of this study was 

eliminated for 2007 and 2008. In lieu of a telemetry effort, we focused our effort on characterizing 

foraging habitat of murrelets in Aialik Bay and Northwestern Lagoon. We intended to also include 

marine bird surveys in the East Arm of Nuka Bay during each sampling period; however, weather 

and logistical constraints precluded surveys in the area during the early season in 2008, and late 

season in 2006 and 2008. Likewise, poor weather and other logistical constraints prevented us 

from conducting dedicated productivity surveys in 2008. 

3 
At-Sea Surveys 

To document the distribution and abundance of Brachyramphus murrelets in Kenai Fjords, 

the coastal and offshore areas of Kenai Fjords were sampled during the 2006–08 breeding seasons 

(fig. 2). Coastwide surveys were conducted in the middle (late June to mid-July) of the expected 

breeding season in order to estimate the recent (2006-08) population size of Kittlitz’s and marbled 

murrelets. We did attempt to schedule surveys as early as possible during this time period (that is, 

starting in late June) but scheduling a vessel for the work at that time was not always possible. 

Aialik Bay, Northwestern Lagoon, and when possible, the East Arm of Nuka Bay, also were 

surveyed early in the season (late May-early June) and later in the season (early to mid-August) to 

characterize the abundance and distribution of both murrelet species during the breeding season 

(table 1). 

In 2006, a systematic sampling design with a combination of coastal and offshore transects 

was established. The coastal transects were created by dividing the entire coastline of Kenai Fjords 

National Park and the adjacent islands (from Callisto Head to Gore Point) into 4-km segments 

using a geographic information system (GIS). After selecting a random starting point, one out of 

every three of the 4-km segments was systematically selected to be surveyed. To create the 

offshore transects for the survey, parallel lines running from east to west and spaced every 0.93 

km (30 seconds of latitude) were drawn for each major bay along the Kenai Fjords coast. Because 

previous surveys indicated that Kittlitz’s murrelet distribution is restricted to the upper sections of 

Aialik Bay and in Northwestern Lagoon, coverage of these areas was increased. Offshore transects 

in Upper Aialik Bay and Northwestern Lagoon were spaced every 1.9 km (1 minute of latitude). 

All surveys were conducted following strip survey protocols established by the U.S. Fish 

and Wildlife Service for surveying marine birds (Gould and Forsell, 1989), with modification for 

working in coastal nearshore waters from small boats (Agler and others, 1998) and continuously 

counting flying birds. All surveys in 2006 were conducted from a 4.8 m Naiad® rigid-hulled 

inflatable skiff. In 2007, surveys within more exposed waters were conducted from the 15.6 m 

M/V Alaskan Gyre. In 2008, the subset of transects (fig. 2), repeated in Aialik Bay and 

Northwestern Lagoon during early, middle, and late-season sampling periods, was surveyed from 

the M/V Alaskan Gyre to accommodate concurrent shipboard hydroacoustic and 

thermosalinograph sampling (see section “Marine Habitat”). For all survey periods and vessel 

types in 2006 and 2007, two observers identified birds and mammals within 100 m of either side 

or 200 m forward of the vessel, resulting in a 200 m wide survey strip. In 2008, strip-width for 

transects conducted from the M/V Alaskan Gyre (only) were increased to 300 m effective width 

(150 m on either side of the vessel) because of improved sighting conditions at increased observer 

altitude (Becker and others, 1999). Ground speed when conducting surveys generally was held 

between 9 and 22 km/h. Speed during bird surveys conducted concurrently with hydroacoustics 

(see section, “Hydroacoustics”) generally was held between 9 and 11 km/h. 

All birds and mammals were identified to species whenever possible. Identification of 

murrelets within the genus Brachyramphus can be particularly difficult given the similarity in size, 

shape, and plumage. Survey crews slowed the vessel when necessary to confirm identification of 

murrelets. A behavior code was assigned to all birds and mammals sighted on transect as either on 

the water (swimming on surface), fish-holding (holding fish in bill), or flying. Bird and mammal 

sightings were recorded by entering them directly into a real-time computer data-entry system 

(dLOG-CE v.1.5.0; Glenn Ford Consulting, Portland, OR) that logs sightings continuously along 

4 
with their GPS coordinates. A waterproof, shock-proof, GPS-enabled hand-held computer (TDS 

Recon®) was used for data entry. Two observers actively scanned ahead of and alongside the 

survey vessel, and species identifications were confirmed using 8–10 power binoculars. Weather 

conditions and sea state were constantly monitored and surveys were not conducted if wave height 

exceeded 0.5 m in height. 

For Brachyramphus murrelets only, the perpendicular distance from the transect line to 

each bird or group of birds also was estimated in order to compare densities observed using 

standard strip and line transect analysis methodology. Although special attention was paid to the 

centerline to ensure all birds were counted, we attempted to estimate distance to all murrelets 

sighted to a maximum distance of 100 m in 2006 and 2007, and a maximum of 300 m in 2008. 

Observer training was conducted prior to each survey using a combination of range finders on 

fixed objects, and bird-sized buoys strung at known distances on a line towed behind the vessel. 

Distance calibration with range finders was reinforced daily throughout each survey. In 2007, 

grouped distance observations (0–20 m, 21–40 m, 41–60 m, 61–80 m, 81–100 m) were recorded, 

whereas in 2006 and 2008, exact distance observations were recorded. 

Productivity Surveys 

Productivity of murrelets was estimated using juvenile to adult ratios from late summer 

counts following Kuletz and Piatt (1999). Productivity surveys in 2006 included a survey of the 

subset of transects in upper Aialik Bay and Northwestern Lagoon on August 12–14 (table 1, fig. 

2), where most fledglings were sighted nearshore. In 2007, the entire shoreline within Aialik Bay 

and Northwestern Lagoon was surveyed on multiple days (fig. 3). Weather and logistical 

constraints hampered dedicated fledgling survey efforts in 2008; however, late season surveys 

corresponded with the timing of murrelet fledging period in nearby Prince William Sound and 

Kachemak Bay (Kuletz and Piatt, 1999; Kuletz and others, 2008). During productivity surveys, all 

murrelets sighted within 100 m of either side of a 4.8 m skiff were identified, enumerated, and 

assigned a plumage and life stage. Perpendicular distances to birds were not recorded. Boat speed 

was usually held between 9 and 22 km/h, but observers stopped the boat when necessary to 

improve accuracy in species and life stage identification. To improve comparisons among years, 

the productivity datasets were refined to include only observations from coastal transects that were 

surveyed in all years. A productivity index (fledglings/adults) was calculated by dividing the 

number of juveniles observed by the number of adults observed. 

Telemetry 

In May 2006, we attempted to capture 20 birds of each species using the night-lighting 

technique (Whitworth and others, 1997) for a radio-telemetry study. We were only able to capture 

eight Kittlitz’s murrelets and no marbled murrelets. All birds captured were weighed, and we 

measured lengths of tarsus, flattened wing chord, culmen, and total length of head and bill 

combined. Each bird also was inspected for a brood patch and the stage if development was noted. 

Radio-transmitters (model A4360; Advanced Telemetry Systems Inc. ®, Isanti, MN) were 

attached to all captured Kittlitz’s murrelets dorsally with commercial-grade adhesive (Slo-Zap®

cyanoacrylate; Pacer Technology, Rancho Cucamonga, CA) and a subcutaneous anchor, following 

Newman and others (1999). Previous radio-telemetry studies of marbled murrelets in British 

Columbia have reported transmitter retention times of 3 to 18 months using this attachment 

method (Nadine Parker, Simon Frasier University, oral commun., 2006; Russell Bradley, Simon 

Frasier University, oral commun., 2006). The transmitters were mounted along the dorsal mid-line 

5 
of each bird and centered between the scapulae. The model A4360 transmitters weigh 

approximately 3.2 g, which equals less than 2 percent of the mean body mass of Kittlitz’s murrelet 

adults (238 ± 4 g, n = 20) captured during a previous study in Glacier Bay National Park (Romano 

and others, 2007b). To decrease the amount of wing-loading stress, transmitter mass should not 

exceed 2–3 percent of body mass for flying birds (Kenwood, 2001). 

Surveys were done from small boats and fixed-wing aircraft to relocate radio-tagged birds. 

The primary vessel for the boat surveys was a 4.8 m Naiad® rigid-hulled inflatable. Boat-based 

surveys were limited to Aialik Bay, Harris Bay, and Northwestern Lagoon and were done 

opportunistically as weather and time allowed. During boat-based surveys a radio receiver (model 

R2000; Advanced Telemetry Systems Inc., Isanti, MN) was connected to a hand-held threeelement Yagi® antennae. One observer monitored the receiver while a second observer scanned 

the water with binoculars looking for birds. 

Aerial telemetry surveys were done from a Cessna® 305A equipped with two wing strutmounted H antennas with a radio receiver connected to the antennas through a switch box 

(Kenwood, 2001). This arrangement facilitates more efficient tracking of signals because the 

observer can determine which side of the aircraft a signal is coming from by listening through 

each antenna independently and comparing the strength of the signals. Eight telemetry flights were 

flown from May 26 through July 1, 2006. Flights departed from Seward or Homer, Alaska, and 

covered the coastal area between Seward and Nuka Bay during each flight. The entire length of 

each bay along the coast was flown at an average altitude of between 600 and 900 m. The flights 

also covered the ice-free upland area in each bay between the water and the Harding Icefield (fig. 

4). The flights originating in Homer covered a broad region including Kachemak Bay, the 

southwest corner of the Kenai Peninsula, and the upland area between Kachemak Bay and Nuka 

Bay. 

Marine Habitat 

Marine habitat characteristics within Aialik Bay and Northwestern Lagoon were examined 

during the 2007 and 2008 field seasons. Sampling covered approximately 25 km from the face of 

the glaciers to the outer fjord stations in each fjord. In July 2007, a pilot study was done to 

measure marine habitat characteristics using a stratified random sampling approach, and in 2008, a 

monthly systematic sampling approach was used to increase effort along established oceanography 

stations and bird survey transects. Sampling included oceanographic measurements, 

ichthyoplankton and zooplankton collections, water samples, and hydroacoustics. 

Oceanography 

Oceanographic gradients in the marine environment were measured by conducting 

oceanography surveys at sample sites established by Gay and Armato (1998) in Aialik Bay and 

Northwestern Lagoon (fig. 5). In 2007, oceanographic surveys were done in conjunction with 

early and late-season bird surveys. In 2008, oceanographic surveys also coincided with the timing 

of hydroacoustic surveys (described below). At each station, we deployed a conductivitytemperature-depth profiler (CTD, SeaBird Electronics® SBE-19) equipped with a fluorometer 

(WetLabs® WetStar). In June and July 2008, additional sensors were used, including a dissolved 

oxygen sensor (SeaBird Electronics® SBE-43), photosynthetically active radiation (PAR) sensor 

(Biospherical® Quantum Scalar 2300L), and a beam transmissometer (WetLabs® C-STAR). In 

August 2008, all external sensors failed and only CTD data were available. 

6 
Environmental and biological parameters were sampled in 2008 at a subset of 

oceanographic stations including two inner-fjord and two outer fjord stations, hereinafter referred 

to as glacial and distal stations, respectively (fig. 5). A water sampler (Seabird Electronics® SBE 

55) was deployed in conjunction with the CTD and water samples were collected at discrete 

depths of 2 and 10 m. Nutrient samples from 2 and 10 m depths were frozen in the field and 

analyzed for ammonium ( ), phosphate ( ), silicic acid ( ), nitrate ( ), and 

nitrite ( ) concentrations at the Marine Chemistry Lab of the University of Washington. 

 NH43 PO4 4 )OH(Si  NO3

 NO2

Tidal Current Velocity 

Tidal current velocities were mapped in Aialik and Northwestern Lagoons on August 14–

17, 2007, using a 600 kHz acoustic Doppler current profiler interfaced with a differentially 

corrected GPS. Typically, lower frequency units are used in marine applications, but the higher 

frequency unit was better suited for shallow and high velocity conditions found at the submerged 

moraines. Measurements of tidal discharge were made at the submerged glacial moraine that 

separates Northwestern Lagoon and Harris Bay, and at the submerged glacial moraine that extends 

from Pedersen Lagoon to Coleman Bay in Aialik Bay. The acoustic Doppler current profiler was 

deployed using a small trimaran that was towed by an inflatable boat. Data were collected during 

peak ebb and flood tides and at slack tide. The path of data collection was normal to the primary 

direction of tidal flow. This cross-section pattern provided a quantification of tidal discharge 

fluxing in and out of the fjords during tidal shifts. Concurrent conductivity, temperature, depth, 

and salinity measurements were made with each cross section. 

Zooplankton 

Mid-water trawls were done to assess community structure of prey relative to glacial 

features in Aialik Bay and Northwestern Lagoon. In 2007, a large IKMT was deployed at 21 

randomly selected stations stratified by distance to glacial features in Aialik Bay and Northwestern 

Lagoon during a cruise from June 29 to July 3 (fig. 6). The large IKMT was 6 m long with a 3.05 

m depressor bar, 7.68 m2

 mouth opening, and 3 mm knotless nylon mesh. The collection cup at the 

cod end had 1 mm mesh screen. Each station was sampled for 30 minutes, for an average transect 

length (± SD) of 2.9 ± 0.38 km. This net was effective at catching ichthyoplankton and 

macrozooplankton, but the large depressor bar made the net more difficult to deploy and so a 

smaller net was used in 2008. 

In 2008, a smaller IKMT was deployed at the same subset of oceanography stations 

described above (fig. 5). The small IKMT was outfitted with 1.8 m depressor bar, 3 mm stretched 

knotless mesh near the mouth, and a 333-μm mesh ring net, which comprised approximately twothirds of the body including the cod end. The net was deployed in an oblique manner and outfitted 

with a depth sensor (VEMCO® minilog T data logger, or Star Oddi® DST CTD) to assess the 

maximum trawl depth. A flowmeter (General Oceanics®) was attached to the mouth of the net to 

estimate distance through the water. Maximum depth towed was 35 m, average (± SD) distance 

towed was 1.2 ± 0.1 km, and speed during the tow was held at approximately 5.5 km/h. One outer 

station in Harris Bay could not be sampled with the IKMT during the early-season cruise because 

of inclement weather. 

7 
For both types of IKMT hauls, total catch volume was estimated to the nearest 10 mL after 

water was drained through sieves. Gelatinous zooplankton, including ctenophores and cnidarians, 

were separated and their volume was estimated as above. Individual ctenophores and cnidarians 

were not identified to species or enumerated as a result of damage to individuals during capture. 

All fish collected in IKMT hauls were identified to species and fork lengths (FL) were measured 

to the nearest 1.0 mm. Fish that could not be identified in the field were preserved in 10 percent 

formaldehyde in seawater solution and returned to the laboratory for later identification. 

Small zooplankton species were sampled with a 211 μm, 0.6 m ring net on a 50 m (or to 

within 5 m from the bottom) vertical haul at the end of each IKMT haul in 2007 and 2008. 

Volume filtered was measured with a flowmeter (General Oceanics®). 

IKMT and ringnet zooplankton sample contents were preserved in a 3–5 percent buffered 

formaldehyde and seawater solution. Samples were identified to species (or lowest possible taxon) 

and developmental stage, enumerated, and damp dry weights measured to the nearest 0.01 mg (or 

for organisms weighing more than 100 mg, to the nearest milligram) under contract with the 

University of Alaska Fairbanks. After rare organisms were removed and counted, large samples 

were subsampled with a Folsom® plankton splitter. 

Hydroacoustics 

In June, July, and August 2008, biomass of fish, zooplankton, and other nekton taxa were 

estimated during hydroacoustic surveys that were done concurrently with seabird surveys at a 

subset of transects in Aialik Bay and Northwestern Fjord (fig. 2). A single beam, 120 kHz 

transducer (Biosonics DT-X®) deployed from a hydrodynamic fin was towed along side of the 

boat at an approximate depth of 2 m below the surface. The vessel generally traveled at speeds 

between 9 and 11 km/h; however, ice obstructions near the head of the fjords forced us to slow the 

vessel to 5 km/h at times. The instrument had a beam angle of 6.5° and collected data at 2 pings/s 

and with a pulse length of 0.5 ms. Field calibration was conducted according to Foote and others 

(1987) on June 2 and July 11, 2008, using a 33 mm standard calibration sphere of known target 

strength. During hydroacoustic/bird transects, a thermosalinograph (Seabird Electronics® SBE 45 

MicroTSG) was deployed to identify surface temperature and salinity conditions. 

Nearshore Fish 

Nearshore fish were sampled with a beach seine at beaches suitable for seining and near 

foraging birds (fig. 5). The beach seine was 37 m long, with mesh size between 28 mm at the 

wings and 5 mm at the center. The seine was set parallel to shore from a skiff and retrieved from 

the beach by two or three people. The catch was put into a holding bucket, identified, counted, and 

as many as 25 haphazardly selected individuals from each species were measured (fork length in 

millimeters). At each site, we recorded location coordinates, sediment type, incline of beach (high, 

moderate, low), and percent cover of kelp swept with the net. 

8 
Data Analysis 

Mid-season transects were stratified in relation to their position relative to the sills in 

Aialik Bay, Northwestern Lagoon, and the East Arm of Nuka Bay (fig. 7). The “Fjords” strata 

consisted of coastal (less than 200 m from shore) and offshore (greater than 200 m from shore) 

transects north of the prominent marine sills within Aialik Bay, Northwestern Lagoon, and the 

East Arm of Nuka Bay (fig. 1). The “Bays” strata consisted of coastal and offshore transects 

outside of the Fjords strata (fig. 7). These strata were selected a priori because previous work in 

Kenai Fjords had shown that murrelet density and distribution differed with distance to shoreline 

and relation to marine sills (Van Pelt and Piatt, 2003). ArcGIS v. 9.2 (ESRI®, Redlands, CA, 

USA) software was used to create the strata and estimate area within each stratum. 

A population estimate was generated for Kittlitz’s, marbled, and all Brachyramphus 

murrelets from the mid-season survey data stratified by area for each year using Program 

Distance® v. 6.0 (Thomas and others, 2009). For analyses of line transect and strip transect data, 

observations were truncated at 100 m to allow comparisons with survey periods and with previous 

surveys. Densities of birds on the water were estimated using line transect methodology and 

densities of birds in the air were estimated using strip transect methodology. Flying birds were not 

included in line transect estimates because of the difficulty of estimating perpendicular distance to 

flying birds, and because detection of flying birds would differ from that of stationary birds. A 

final population estimate was calculated as the sum of the stratified line transect estimate for birds 

on the water and stratified strip transect estimate for birds in the air. 

For line transect estimates of birds on the water, detections were modeled as clusters, or 

observations of single or groups of birds sitting on the water. Detection functions for line transects 

are not reliable with fewer than 60–80 detections (Buckland and others, 2001), and in some or all 

strata-year combinations, there were not enough detections by species for a robust sighting 

probability model. Therefore, a global detection function for all Brachyramphus murrelets was 

applied to each species’ distance data for each stratum-year combination. If the sighting 

probability of murrelets in coastal strata was less than one at 100 m from the transect line, we 

applied the detection function for offshore transects (Kissling and others, 2007). Candidate models 

included uniform and half-normal keys with cosine, polynomial, or hermite adjustment terms. The 

most parsimonious sighting probability models were selected on the basis of Akaike Information 

Criterion (AIC) values. Strip transect estimates of flying birds were modeled using a uniform key 

and cosine adjustment. For all models, variance was estimated empirically, cluster size was 

determined by the mean, and non-parametric bootstrap was applied by resampling samples within 

strata 999 times (Efron and Tibshirani, 1986). Pooled densities were calculated as the mean of 

stratum density weighted by stratum area, and population size was calculated as the sum of 

stratum density multiplied by stratum area. Log-based confidence intervals were computed 

according to Buckland and others (2001). 

Early, middle, and late season densities of murrelets were calculated using a ratio estimator 

(Agler and others, 1998; Kuletz and others, 2008) for a subset of transects repeated in Aialik Bay 

and Northwestern Lagoon for each year (fig. 2). For each survey, distance data were used to 

estimate a detection function for all Brachyramphus murrelets on offshore transects, and the 

resulting effective strip half width (ESW) was used to correct stratified density estimates when the 

sighting probability was less than 1 across the 200 m strip width. Raw counts of birds were 

prorated to proportionately allocate unidentified birds into density estimates of each murrelet 

species, using the ratio between Kittlitz’s and Marbled murrelets positively identified on a 

9 
transect-by-transect basis. After summing the count of birds by transect, and setting a single 

interval distance at the ESW for offshore transects, stratified density estimates were computed 

using a uniform key and cosine adjustment in Program Distance®. Within-season density was 

calculated for raw and prorated counts of Kittlitz’s and Marbled Murrelets. A productivity index 

was calculated for Kittlitz’s and Marbled murrelets following Kuletz and Piatt (1999), including 

only coastal transects repeated in each year. A t-test was used to compare measurements of 

captured birds from Kenai Fjords in 2006 to captured birds from Glacier Bay National Park in 

2004 (Romano and others, 2007a). 

Raw CTD data were processed through SBE Data Processing modules v. 7.18 (Sea-Bird 

Electronics, Bellevue, WA, USA). Photic depth was calculated as the depth at which PAR values 

dropped to 1 percent of surface values. Water column profile data were contoured in MATLAB®

v. 7.5 (MathWorks, Natick, MA, USA) relative to depth and station distance along a line drawn 

between the head of the fjord and the outer-most station. 

Spatial and temporal differences in abiotic and biotic datasets were tested with two-way or 

three-way fixed effects ANOVA using JMP® v. 7.0.2 (SAS Institute, Cary, NC, USA), including 

within fjord (glacial versus distal), between fjord (Northwestern versus Aialik), and month factors. 

Response variables were tested for normality using Shapiro-Wilks, and homogeneity of variance 

was assessed through residual plots and Levene’s tests at α < 0.05. For multi-factorial tests, when 

interaction terms were not significant, additive models were applied. Data were transformed to 

induce normality, or a Spearman rank correlation was used when assumptions of normality and 

homoscedasticity were not satisfied. 

Multivariate statistical analyses of trawl catch community structure were conducted in 

PRIMER® v. 6 (PRIMER-E Ltd & PERMANOVA 1.0.1, Lutten, Ivybridge, UK). Prior to analysis 

of trawl catch community structure, we reduced the dataset to include species that are important in 

murrelet diets, including euphausiids, copepods (by species), shrimp, amphipods, capelin, and 

gadids. Gelatinous zooplankton also were included because they likely influenced community 

structure and associations with Kittlitz’s murrelets have been observed in Glacier Bay (J. Piatt, US 

Geological Survey, unpublished data, 2004). The Bray-Curtis similarity measure was computed on 

abundance data that were first log (x+1) transformed and standardized. We tested for homogeneity 

of multivariate dispersions in species composition between levels of factors. Factors included 

glacial influence (glacial versus distal stations), month, and location (Aialik versus Northwestern). 

Homogeneity of multivariate dispersions was met for glacial influence (PERMDISP: F[1,21] = 3.97, 

p = 0.07) and location (PERMDISP: F[1,21] = 0.63, p = 0.47) factors, but it was rejected for the 

month factor (PERMDISP: F[1,21] = 4.00, p = 0.05). Pairwise tests indicated July and August 

samples were not significantly different from one another (p = 0.27). A 3-way fixed effects 

permutation-based MANOVA was used to test for differences in zooplankton species 

composition. When interaction terms were not significant at α = 0.05, additive models were used. 

Contributions of individual species to community structure were examined using the SIMPER 

routine. 

Hydroacoustic data were integrated with Echoview® v. 2.10 software (SonarData Pty. Ltd., 

Hobart, Tasmania, AUS). Noise was reduced by setting a minimum threshold for integration at 

-80 dB. Sound speed and absorption coefficients were determined from CTD casts. Surface noise 

and the bottom signal, determined by visually examining the echograms, were excluded from the 

analysis. Additionally, the data for the upper 1 m were removed to eliminate the effects of 

collecting data in the near field of the transducer, which resulted in the effective minimum depth 

of acoustic measurements at 3 m below the surface. The integration output for acoustic backscatter 

10 
was expressed as nautical area scattering coefficient (NASC), and was used as a proxy for 

biomass. NASC was summed over the upper 40 m (NASC40) of the water column to estimate 

biomass available within the diving depth of Kittlitz’s murrelets (maximum approximately 35–40 

m, Day and others, 1999). NASC40 over the length of each transect was summed and divided by 

the transect length (sum of NASC40 / km) to standardize by effort. Distance from the midpoint of 

each acoustic transect to the nearest tidewater glacier was estimated in GIS. A 2-way ANOVA 

was applied to acoustic data summed by transect to test for differences between fjords and months. 

Least squares linear regression was used to examine the relationship between the log-transformed 

sum of NASC40 / km and the transect distance to nearest tidewater glacier by month and fjord. 

To assess changes in schooling fish distribution over the course of the 2008 breeding 

season, dense fish aggregations were separated from more dispersed prey and weaker scattering 

targets as in Mehlum and others (1996). Dense forage fish aggregations encountered on 

hydroacoustic surveys were integrated by month by visually examining the echograms, identifying 

regions containing dense aggregations of fish, and integrating aggregations separately from 

weaker scattering organisms, such as zooplankton and dispersed fish. Dense schools of fish 

typically are distinct in their shape and target strength characteristics compared to weaker 

scattering organisms (Simmonds and MacLennan, 2005). 

To relate Kittlitz’s and marbled murrelet distribution in Aialik Bay and Northwestern 

Lagoon to environmental variables, we used a combination of generalized linear models (GLM) 

and generalized linear mixed effects models (GLMM) using survey data, bathymetry, and 

concurrent hydroacoustic and thermosalinograph data from July 2008. Raw point data from 

marine bird and acoustic transects in Aialik Bay and Northwestern Lagoon (fig. 2) were divided 

into 200, 400, 800, and 1,600 m segments, aggregated by segment, and analyzed using R statistical 

software v. 2.7.2 (R development Core Team, 2008). For each distance class, the response variable 

was presence/absence of murrelets (by species) within each segment, and independent variables 

were calculated as the mean acoustic biomass, sea surface salinity, and bottom depth within each 

segment. Distance from the midpoint of each transect segment to the nearest tidewater glacier also 

was included as an explanatory variable. Ice presence/absence, fjord (Aialik Bay or Northwestern 

Lagoon), and transect type (coastal or offshore) were coded as a categorical variables. Prior to 

analysis, we log (x + 0.0001)-transformed mean acoustic biomass and then normalized continuous 

variables. Sea surface temperature was not included as an independent variable because it was 

highly correlated with glacier distance. The presence or absence of murrelets was coded as a 

binary response (0/1) and the probability of observing murrelets along a given segment was 

modeled as a function of the predictor variables using a GLM with a binomial error distribution 

and a logit link. The best GLM models were selected on the basis of AIC values. Kittlitz’s 

murrelets were never present where ice was absent; modeling of habitat preferences was therefore 

restricted to those observations where ice was present. To account for spatial autocorrelation 

between segments on a single transect, we followed the exploration of candidate GLM models 

11 
with GLMM models that incorporated spatial autocorrelation within transects and allowed for 

random differences in the mean response (probability of occurrence) among transects (Dormann 

and others, 2007). The correlation structure was modeled as an exponential spatial correlation 

using the following equation: 















   p

d

df ij

ij exp)( (1) 

where 

dij is equal to the distance between two observations, and 

p is the range coefficient. 

The performance of the final models in predicting presence/absence of murrelets was evaluated 

based on the proportion of fitted probabilities that resulted in correct classification of the response 

(presence/absence), whereby a predicted probability of greater than or equal to 0.5 was considered 

to indicate presence. Although we examined models at multiple scales, only the most 

parsimonious model with the highest correct prediction rate for each species is presented. 

Results 

Population, Distribution, and Abundance 

During the 2006–08 murrelet breeding seasons, a total of 506 transects and a sampling area 

of 416 km2

 were surveyed (table 1). To estimate the population of murrelets in Kenai Fjords, we 

surveyed between 11.9 and 12.8 percent of the total area with 100, 90, and 99 transects in 2006, 

2007, and 2008, respectively (table 2). 

We counted 7,879 murrelets over the course of this study, of which Kittlitz’s murrelets 

comprised 8.9 percent, marbled murrelets 87.1 percent and unidentified Brachyramphus murrelets 

3.9 percent of all observations. Data were collected on all marine birds and mammals sighted 

during the surveys and total counts of those observations are presented in appendixes 1–3. 

The overall mean group size (± SE) for Kittlitz’s murrelets was 1.59 ± 0.07 birds/group 

and was slightly higher for marbled murrelets at 1.99 ± 0.03 birds/group. Group size ranged from 

1 to 11 birds/group for Kittlitz’s murrelets and 1 to 50 birds/ group for marbled murrelets. 

Kittlitz’s Murrelets 

We estimated that the population (and 95% CI) of Kittlitz’s murrelets in Kenai Fjords 

National Park was 925 (393–2,179) birds in 2006, 423 (252–709) birds in 2007, and 664 (294–

1,499) birds in 2008 (table 3). Between 0 and 19.8 percent of birds observed flying during surveys 

were identified as Kittlitz’s murrelets (table 4). 

Marbled Murrelets 

The estimated population of marbled murrelets was 6,418 (4,730–8,709) birds in 2006, 

3,619 (2,371–5,524) birds in 2007, and 7,529 (5,546–10,222) birds in 2008 (table 3). Marbled 

murrelets comprised between 0.6 and 4.7 percent of all flying murrelets (table 4). 

12 
Brachyramphus Murrelets 

Total population estimates for all Brachyramphus murrelets in Kenai Fjords were 7,586 

(5,344–10,768) in 2006; 4,424 (3,099–6,315) in 2007; and 9,677 (7,449–12,571) in 2008 (table 3). 

Unidentified Brachyramphus murrelets comprised between 10.8 and 82.4 percent of flying 

murrelet observations (table 4). 

Density 

Density estimates for all Kittlitz’s murrelets sighted within 100 m of either side of the 

vessel on the subset of transects repeated in Aialik Bay and Northwestern Lagoon during all years 

were on average (± SE) 2.74 (± 0.27) birds/km2

 in the early season, 2.67 (± 0.67) birds/km2 for 

mid-season, and 1.10 (± 0.35) birds/km2

 for late season surveys (table 5). In 2006 and 2008, 

Kittlitz’s murrelet density increased from early to mid-season, followed by a decrease late in the 

season. In 2007, density decreased between early and mid-season, and late season density 

remained relatively stable through late-season surveys. Additionally, in 2007, late season density 

was higher although the coefficient of variation was lower than in 2006 and 2008 (table 5). During 

mid-season coastwide surveys, the average density for Kittlitz’s murrelets was highest in the fjord 

offshore stratum (table 6, fig. 8), with average density (± SE) of 5.97 (± 1.58) birds/km2

 across 

years, and it was lowest in the bays offshore stratum with an average (± SE) density of 0.02 (± 

0.02) birds/km2

 across years. When raw counts of Kittlitz’s murrelets were prorated for 

unidentified birds, average densities were 2.91 (0.34) birds/km2

 in the early season, 2.85 (0.66) 

birds/km2

 in the mid-season, and 1.18 (0.43) birds/km2 in the late season (table 5). Prorated 

estimates increased Kittlitz’s Murrelet within-season density estimates by an average of 5.6 (2.9) 

percent. Lowest variability in Kittlitz’s Murrelet density occurred in the early season surveys 

(table 5). 

Density estimates for all marbled murrelets on transects repeated throughout the 2006–08 

summers were on average (± SE) 13.75 (± 2.75) birds/km2

 in the early season, 15.72 (± 1.68) 

birds/km2

 in the mid-season, and 33.88 (± 7.18) birds/km2 in the late season (table 5). Coefficients 

of variation ranged from 19.7 to 32.8% in the early season, 24.8 to 38.1 percent in the mid-season, 

and 21.3 to 21.6 percent in the late season. Similar to Kittlitz’s murrelets density patterns, marbled 

murrelets had lowest densities in the early season compared to middle and late season estimates in 

2006 and 2008, whereas monthly densities were lowest during the mid-season survey in 2007. The 

highest density of marbled murrelets occurred during the late season survey in 2007, with an 

average (± SE) of 46.77 (± 9.98) birds/km2

. During mid-season coastwide surveys, average 

density of marbled murrelets was highest in the fjord coastal stratum (table 6, fig. 9). When raw 

counts were prorated for unidentified birds, average density of Marbled Murrelets was 14.33 

(3.09) birds/km2

 in the early season, 16.46 (2.22) birds/km2 in the mid-season, and 35.31 (7.97) 

birds/km2

 in the late season (table 5). Prorating counts increased Marbled Murrelet within-season 

density estimates by an average of 3.6 (1.9) percent. Lowest variability in Marbled Murrelet 

density occurred during the mid-season surveys (table 5). During mid-season coastwide surveys, 

the average (± SE) marbled murrelets density for all years was highest in the fjord coastal stratum 

(table 6) with 25.32 (± 4.00) birds/km2

, and lowest in the bays offshore stratum with 7.15 (± 1.85) 

birds/km2

. 

13 
Productivity 

A total of 421 adults and 13 marbled murrelet fledglings were observed on transects in 

Northwestern Lagoon and Aialik Bay on August 12–14, 2006. The majority of marbled murrelet 

fledglings (85 percent) were sighted on coastal transects (fig. 10). Seven adult and no Kittlitz’s 

murrelet fledglings were observed on transect. 

In 2007, we covered 172.6 linear km for a survey area of 34.5 km2

 during the first set of 

transects on August 9–11, and 84.0 linear km for a survey area of 16.8 km2

 during the second set 

of transects on August 14–17. A total of 51 adult Kittlitz’s murrelets were observed during 

fledgling surveys in 2007. Twenty-nine adults in alternate plumage and one adult in basic plumage 

were sighted during the first juvenile survey, and 21 adults in alternate plumage were sighted 

during the second juvenile survey. One adult was observed holding a juvenile Pacific herring in 

Northwestern Lagoon on August 16, 2007. No hatch-year or possible hatch-year Kittlitz’s 

murrelets were observed in 2007. The majority of Kittlitz’s murrelets were sighted in the glaciated 

area near the head of Northwestern Lagoon. 

During fledgling surveys in 2007, we observed 1,866 adult, 5 hatch-year, and 1 possible 

hatch-year marbled murrelets. Three adults were in basic plumage, one adult was in intermediate 

plumage, and the remaining adults were in alternate plumage. Ten adults were carrying fish—one 

carrying a capelin, eight each carrying a juvenile Pacific herring, and one carrying a Pacific sand 

lance. 

In 2008, 15 adults, and a single juvenile Kittlitz’s murrelet were observed on late season 

surveys in Aialik Bay and Northwestern Lagoon. The juvenile Kittlitz’s murrelet was the only 

fledgling observed during the course of the study, and its identification was confirmed with a 

photograph. There were 556 adult marbled murrelets, one fledgling, and two possible fledglings 

sighted on transect. All adult Kittlitz’s murrelets, and all but one adult marbled murrelet were in 

alternate plumage. We observed 1 Kittlitz’s murrelet and 16 marbled murrelets carrying fish, but 

no fish were identified to species. 

A productivity index (juvenile: adult ratio for surveys data effort was repeated during all 3 

years) for Kittlitz’s murrelets was 0 in 2006 and 2007, and 0.1 fledglings/adult in 2008. A 

productivity index for marbled murrelets for the same coastal area was 0.03 fledglings/adult in 

2006, 0.01 fledglings/adult in 2007, and 0.002 (0.006 if possible hatch year birds are included) 

fledglings/adult in 2008. 

Observations of Radio-Marked Kittlitz’s Murrelets 

Eight Kittlitz’s murrelets were captured during the night on the water between May 7 and 

13, 2006. Two of the birds were caught as a pair, in a single scoop of the dipnet. Of the single 

birds captured, most were sighted on the water with a partner but only one of the pair was pursued. 

The weather, sea conditions, and extent of ice greatly limited capture possibilities and success. 

The capture success rate was less than 50 percent for birds positively identified on the water. Rain 

and sea conditions limited the visibility of the observers and sea conditions also limited the 

maneuverability of the capture vessel. 

14 
The body measurements of the 8 birds captured in Kenai Fjords were compared to a 

sample of 20 Kittlitz’s murrelets that were captured in Glacier Bay National Park during May 

2004. The birds captured in Kenai Fjords had significantly lower body mass than birds captured in 

Glacier Bay (p < 0.05; table 7). In contrast, there was no difference between the two groups in 

length of tarsus (p = 0.09), wing (p = 0.41), and culmen (p = 0.39). In general, most of the birds 

captured in Kenai Fjords were either in basic plumage or just beginning the molt into breeding 

plumage. Most of the birds showed little or no development of the brood patch at the time of 

capture. 

There were 47 relocations recorded on the surveys and every bird was relocated at least 

once (fig. 11). No bird was located farther than 10 km from its capture site. Two of the radiomarked birds were confirmed depredated and their transmitters were recovered with remains of 

feathers. A third bird was tracked to an eagle nest and presumed depredated but the transmitter 

was not recovered. Bird 06-004 was tracked to a location on land on May 30, and relocated at the 

same location on June 1 and June 7. This bird was not located on any other survey after June 7 and 

its fate is unknown. 

Marine Habitat 

Oceanography 

Water column profiles showed spatial and temporal differences in temperature and salinity 

between glacial and distal areas in both fjords (fig. 12). Temperature and salinity profiles 

demonstrated the importance of marine sills in the exchange of inner and outer fjord waters. The 

cool, low-salinity waters pooled behind the sills in the inner fjord, and warmer, more saline water 

was held outside of the sills. The sill in Northwestern Lagoon is shallower and the passage is more 

constricted than in Aialik Bay. Surface freshening in Northwestern Lagoon extended deeper into 

the water column than in Aialik Bay during all sampling periods of the study. 

Chlorophyll a concentrations, used here as a proxy for phytoplankton standing crop, were 

lowest in both fjords during June 2007 (fig. 13). In general, chlorophyll a concentrations were 

consistently higher in Northwestern Lagoon compared to Aialik Bay, particularly in August 2007. 

Low photic depth near the glaciers corresponded with low chlorophyll a concentrations. 

Surface water clarity was lowest near tidewater glaciers, and decreased between June and 

July 2008 (fig. 14). In July, low water clarity over the upper 50 m of the water column less than 3 

km from Aialik Glacier indicated increased glacial runoff. Beam transmission in the upper 3 m of 

the water column at stations within 3 km of tidewater glaciers was on average (± SE) 54.61 ± 9.58 

percent in June, and 28.36 ± 6.76 percent in July. In contrast, average (± SE) beam transmission 

below 3 m depth at stations within 3 km of a tidewater glacier was 87.52 ± 0.94 percent in June 

and 79.54 ± 5.16 percent in July. The median depth of 80 percent water clarity occurred at 5 and 

6.5 m in June and July, respectively, for Aialik Bay stations, and at 9 m in both June and July in 

Northwestern Lagoon. Two stations sampled within 1 km from Aialik Glacier in July had low 

water clarity throughout the water column, with maximum water clarity of 73.46 percent at 99 m, 

and 66.6 percent at 88 m (fig. 15). 

15 
In 2008, average dissolved inorganic nitrogen (DIN) concentrations generally decreased 

throughout the summer and were higher in glacial areas than distal areas (table 8). Fourth roottransformed DIN differed between glacial and distal areas, and among months, but did not differ 

significantly between fjords (3-way ANOVA: F[3, 21] = 4.15, R2

 = 0.45, p < 0.05). DIN was 

significantly higher in June than July and August, but July and August were not significantly 

different from one another (Tukey HSD, α = 0.05). Average (± SE) DIN to phosphate ratios were 

2.70 ± 0.58 μM at the surface and 4.30 ± 0.57 μM at 10 m depth and were well below the Redfield 

ratio of 16:1 (Redfield, 1958) during all sample periods. Surface values of Si(OH)4 were lowest in 

Aialik Bay in July and in Northwestern Lagoon in August (fig. 15). 

Ammonium concentrations in the surface waters differed within and between fjords. In 

July 2007, ammonium concentrations were significantly different between glacial and distal 

stations, but not between Northwestern Lagoon and Aialik Bay (2-way ANOVA: F[2,19] = 5.45, R2

= 0.36, p < 0.05). In 2008, fourth root-transformed ammonium concentrations were higher at 

glacial stations compared to distal stations, and also in Northwestern Lagoon compared to Aialik 

Bay (3-way ANOVA: F[4,17] = 3.48, R2

= 0.45, p < 0.05). Ammonium concentrations in June were 

higher than July and August, whereas ammonium concentrations in July and August were not 

significantly different from one another (Tukey HSD, α = 0.05). 

Current measurements at the marine sills in Aialik and Northwestern Lagoons were 

characterized by high velocities and complex flow. The horizontal and vertical contraction of the 

fjord geometry accelerated the tidal currents over the sill and induced three-dimensional currents. 

The maximum tidal discharge measured was 12,300 m3

/s at the marine sill in Aialik Bay during 

the peak flood tide on August 15, 2007. The maximum tidal discharge measured at the marine sill 

in Northwestern Lagoon was 10,100 m3

/s during the peak ebb tide on August 15, 2007. The 

maximum measured velocity of 1.8 m/s was during this measurement. 

In contrast, current measurements made near the front of Aialik and Northwestern Glaciers 

were characterized by low velocity and stratification from freshwater input. Average velocities in 

front of Aialik Glacier were less than 0.01 m/s. Limited data were collected in front of the 

Northwestern Glacier due to thick ice pack, depths in excess of the instrument’s range, and limited 

satellite coverage. Inflow from the glaciers was not distinguishable in the velocity data, but a 

freshwater lens was definable in both the salinity and ADCP measurements of acoustical 

backscatter data (fig. 16). The sediment laden freshwater discharge from Aialik Glacier had a 

higher acoustical backscatter than denser water below the pycnocline. High acoustical backscatter, 

a proxy for turbidity, was strongest in the upper 5 m of the water column, particularly on the 

southern end of Aialik Glacier, which was grounded at low tide. Deeper acoustical backscatter 

near the northern end of the Aialik Glacier face suggested subsurface freshwater flow. 

The current datasets from both Aialik Bay and Northwestern Lagoon sills indicated 

sediment transport along the ocean floor during flood and ebb tides. The measurements along both 

sills showed a discrepancy between the ADCP ship track and the GPS ship track indicating that 

sediment was being transported along the ocean floor at the time of the measurements. The 

divergence of tracks was the result of a bias in the ADCP data that was introduced when sediment 

particles were moving on the bed. The ADCP algorithms interpret the movement of the sediment 

as movement of the ADCP. The GPS data are not affected by this phenomenon and therefore 

represent a more accurate ship track. Sediment transport was detected at both the Aialik and 

Northwestern sills at peak flow. These large discharges and high velocities measured at the marine 

sills act to mix fresh water from the upper fjords with waters from the Gulf of Alaska. 

16 
Prey Availability 

At least 28 species of fish were captured with an IKMT in 2007 and 2008 (table 9), 

including species important in murrelet diets such as capelin, Pacific herring, and Pacific sand 

lance. Saffron cod (Eleginus gracilis) was the most abundant species of gadid. Pacific cod (Gadus 

macrocephalus) and walleye pollock (Theragra chalcogramma) also were present. Mesopelagic 

fishes included lanternfish (Myctophidae) and northern smoothtongue (Leuroglossus schmidti). At 

least 52 species of zooplankton also were collected in 2007 and 2008 (appendixes 4–5). 

At least five species of euphausiid were collected in Kenai Fjords, including (in order of 

abundance) Thysanoessa inermis, T. raschii, Euphausia pacifica, T. spinifera, and T. longipes. In 

2007, trawl-caught euphausiid density was negatively associated with distance to tidewater 

glaciers (Spearman ρ = -0.63, p < 0.01). In 2008, the relationship between euphausiid density and 

glacial distance was not significantly correlated (Spearman ρ June = -0.64, p = 0.12, pJuly = 0.74, 

pAugust = 0.49). 

Trawl catch community structure at glacial and distal stations were not significantly 

different from one another (Pseudo F[1,12] = 1.35, p = 0.22) (table 10). There was a significant 

difference between fjords (Pseudo F[1, 12] = 2.40, p = 0.03) and also between months (Pseudo F[1, 

12] = 7.25, p = 0.003). Eucalanus bungii was consistently more abundant in Aialik Bay and 

contributed most to dissimilarities in community structure between fjords. Centropages 

abdominalis and amphipods were more abundant in Northwestern Lagoon, contributing to 17.7 

percent of the dissimilarity between fjords. Capelin larvae also were more abundant in 

Northwestern Lagoon than Aialik Bay and contributed to 8.0 percent of the dissimilarity between 

fjords. Capelin larvae were most abundant in July and contributed to 13.7 percent of the 

dissimilarity between July and August. Age-0 gadids were most abundant in June and contributed 

to 8.6 percent of the dissimilarity between June and July, and 16.5 percent of dissimilarity 

between June and August. Euphausiids were most abundant in July, and accounted for 6.4 percent 

of dissimilarities between June and July, and 8.1 percent of dissimilarities between July and 

August. Gelatinous zooplankton comprised the lowest proportion of the catch in proximity to 

tidewater glaciers, and a high proportion of the catch at distal stations (fig. 17). 

Hydroacoustic measurements of schooling fish suggested within and between fjord 

differences over the course of the summer in 2008 (figs. 18-19). Dense forage fish aggregations 

were scarce in Northwestern Lagoon during June whereas abundance was highest in July and an 

intermediate in August. Fish aggregations in Aialik Bay were most abundant in distal areas in June 

and in glacial areas by August. Aialik Bay’s northeastern shore in August had more numerous 

schools of greater magnitude than any other area during the summer. Mean (± SE) depth of 

schools was 39.0 ± 6.7 m in June, 46.7 ± 7.4 m in July, and 32.2 ± 3.4 m in August. 

Weaker scattering nekton, including zooplankton and more dispersed fish also showed 

seasonal variability (fig. 18). Acoustic biomass increased throughout the summer in both fjords. 

Higher intensity scattering generally was associated with nearshore areas, marine sills, and 

tidewater glaciers. Net sampling indicated that acoustic biomass in glacial areas primarily was due 

to zooplankton and loose aggregations of fish. In August, weaker scattering organisms were 

abundant in glacial areas of both fjords. 

17 
Acoustic biomass within the upper 40 m of the water column differed significantly by 

month and fjord (2-way ANOVA: F[3,72] = 6.28, R2

 = 0.21, p < 0.001). Biomass was lower in June 

than in July and August, but July and August were not significantly different from each other 

(Tukey HSD, α = 0.05). Biomass in Aialik Bay was significantly higher than in Northwestern 

Lagoon (Student’s t, α = 0.05). The relationship between acoustic biomass and glacial distance 

differed by fjord and month (fig. 19). In Northwestern Lagoon, acoustic biomass was negatively 

associated with distance to glacier in June (R2

 = 0.43, p < 0.05) and July (R2 = 0.35, p < 0.05). In 

Aialik Bay, acoustic biomass was positively associated with distance to glacier in June (R2

 = 0.55, 

p < 0.01), but this pattern did not persist through the summer. 

We conducted a total of 13 beach seine sets at six sites in 2007 and 2 beach seine sets at 

two sites in 2008. At least 21 species of fish were collected in beach seines (table 11). Pacific sand 

lance (n = 1,757), pink salmon (Oncorhynchus gorbuscha, n = 636), and Pacific herring (n = 155) 

were most abundant and all three species occurred in 31 percent of beach seine sets. Pacific sand 

lance were consistently collected at the marine sill in McCarty Fjord and in Northwestern Lagoon. 

Juvenile Pacific herring were collected near the head of Aialik Bay in Northwestern Lagoon, 

Pederson Lagoon, and Verdant Cove. Surf melt (Hypomesus pretiosus, n = 62) also were among 

the more common species, and were caught at the marine sill in McCarty Fjord, Pederson Lagoon, 

and Northwestern Lagoon. A single capelin in spawning condition (spent female) was collected in 

Pederson lagoon on August 3, 2007. 

Fish observed in Kittlitz’s and marbled murrelet bills were juvenile Pacific herring (n = 

15), Pacific sand lance (n = 2), surf smelt (n = 1), and capelin (n = 1). The approximate size of 

herring in bill loads was 95–110 mm, and one sand lance bill load was estimated at 110 mm in 

length. Kittlitz’s Murrelets were observed eating (that is, surfacing with fish and swallowing them) 

herring and sand lance near areas where those species were collected in beach seines. 

Habitat Model 

Habitat preferences differed between Kittlitz’s and marbled murrelets (table 12), despite 

their apparent distributional overlap in Kenai Fjords. Where ice was present, the best model 

showed Kittlitz’s murrelets had a higher probability of occurrence in Aialik Bay, over deeper 

water, closer to the tidewater glaciers, and where acoustic biomass was higher. The probability of 

marbled murrelet occurrence was negatively related to bottom depth and ice cover. The most 

parsimonious models resulted from the 400-m scale for the Kittlitz’s murrelet and 800-m scale for 

the marbled murrelet. A smaller segment size resulted in the best model for Kittlitz’s murrelets 

because data were restricted to observations where ice was present, and greater segment sizes 

resulted in sample sizes that were too low to draw meaningful inference. 

Discussion 

In this section, we first discuss our rationale for survey design including the treatment of 

flying birds, transect methodology, and timing of surveys. We then consider the effects of 

variability in bird distribution over space and time on population estimates for Kenai Fjords. 

Finally, we discuss the overall findings from telemetry, productivity surveys, and marine habitat 

characterization efforts. 

18 
Survey Design 

In 2006–08, a new sampling regime was designed to standardize the study design and 

make the survey easier to replicate in the future. Changes from an earlier survey included orienting 

the offshore transects along latitude lines and creating a new set of systematically selected coastal 

transects to ensure that proper coverage was afforded to the entire coastline. This change in 

transect location may cause issues with direct comparability among years; however, we intended 

for the 2006–08 transects to systematically cover the areas where murrelets are most likely to 

occur while also maximizing repeatability. 

Other considerations for survey design include the treatment of flying birds, survey 

methodology, and timing of surveys. The inclusion of flying birds in population analyses 

overestimates density because the targets move faster than the ship and more birds fly over the 

survey area than are present at one instant in time (Tasker and others, 1984). Therefore, the 

inclusion of flying birds can present a problem for density calculations and population estimates if 

their numbers represent a significant portion of the overall total. Excluding flying birds altogether 

from population analyses, however, underestimates the number of birds in the area. During this 

study, flying birds generally made up about 5 percent or less of Kittlitz’s and marbled murrelet 

observations, with the exception of the mid-season surveys in 2006 when flying birds made up 

nearly 20 percent of Kittlitz’s murrelet observations (table 4). Another issue is that a large 

proportion of flying birds was comprised of unidentified Brachyramphus murrelets (table 4). To 

address these issues, we presented an adjusted total population estimate that includes line transect 

estimates for birds on the water and strip transect estimates for flying birds for Kittlitz’s, marbled, 

and all Brachyramphus murrelets (table 3). 

A combination of strip and line transect methodology was used to more accurately estimate 

population size for Brachyramphus murrelets. Strip transects underestimate marine bird 

population size when observers are unable to detect every bird within the strip (Buckland and 

others, 1993; 2001), for example, if sighting probability decreases with distance from the survey 

vessel. Line transect methodology incorporates detection probability based on perpendicular 

distance of detected birds to the transect line, essentially creating a correction factor for undetected 

birds. Detection probabilities in some but not all stratum-year combinations decreased with 

distance from the vessel. Weather conditions in 2006 contributed to a lower sighting probability of 

murrelets with distance from the ship track on the more exposed outer coast and offshore transects. 

In most strata-year combinations, however, detection of Brachyramphus murrelets was equal to 

one across the strip width. The combined strip and line transect methodology for counting 

murrelets probably is a logistically reasonable way to achieve more accurate population estimates 

than strip transects alone, despite the need for a high level of observer training and constant 

reinforcement of distance calibration. 

When deciding the best time to survey seabird populations for status and trend analysis, 

managers are faced with decisions regarding the tradeoff between statistical significance and 

biological significance, as these are rarely the same (Hatch, 2003). The ability to detect a 

statistically significant trend is strongly dependent on the number and precision of samples 

(Gerrodette, 1987), and so with a reasonable number of samples, the best time to survey birds to 

detect trend is when numbers at sea exhibit the lowest variability. However, a more reasonable 

approach may be to survey at a more biologically significant time (Seavy and Reynolds, 2007), for 

example, when peak numbers of birds are observed at sea to estimate total numbers at sea. The 

trade-off between conducting surveys during timing of lowest variability (early-season, when one 

of the pair is usually sitting on the nest) and timing of maximum density (mid-season, when both 

19 
birds of the pair are actively foraging to feed the chick, and when subadults/non-breeders occur) is 

substantial and can have important consequences for population estimates and trend analysis. For 

murrelets, interannual and within-season variability is high, and so it would be best to conduct 

multiple surveys within a single year (Becker and others, 1999). Timing of highest densities on the 

water (mid-season for Kittlitz’s murrelets, late season for marbled murrelets) did not correspond 

with the timing of lowest variability (usually early season, late May–early June) for murrelets in 

Kenai Fjords during this study, and this concurs with seasonal patterns observed in other studies 

(Speckman and others, 2000; Romano and others, 2004). Historical survey effort for population 

estimation in Kenai Fjords occurred from June 19 to July 14 (Van Pelt and Piatt, 2003) and our 

mid-season surveys are comparable with these historical surveys. The data indicate that the best 

trend information, however, would come from early season surveys (late May–early June) for 

Kittlitz’s murrelets, and from mid-season surveys (late June–early July) for marbled murrelets. 

Population and Distribution 

Based on an average of point estimates for mid-season coastwide surveys in Kenai Fjords, 

the estimated population (± SE) of Kittlitz’s murrelets was 670 (± 144) individuals, and marbled 

murrelets was 5,855 (± 1,163) individuals. The most recent information suggests that this is 

perhaps 3 percent of Kittlitz’s and 2 percent of marbled murrelet Alaska-wide populations (Piatt 

and others, 2007; U.S. Fish and Wildlife Service, 2008). During this study, Kittlitz’s murrelets 

largely were restricted to the areas closest to tidewater glaciers, and nearly always found above the 

sills in McCarty Fjord, Northwestern Lagoon, and Aialik Bay. Marbled murrelets were more 

widely distributed, occurring in both glacial and distal areas of the fjords, and also in the more 

exposed outer coast areas. Although their distribution in the upper fjords overlapped, the two 

species generally utilized different habitats (figs. 8–9). 

Interannual variability in murrelet abundance was high, and these short-term fluctuations in 

the abundance of Kittlitz’s murrelets may have simply reflected regional abundance patterns that 

were concordant with surveys in Kachemak Bay (Kuletz and others, 2008) and Icy Bay (Michelle 

Kissling, U.S. Fish and Wildlife Service, oral. commun., 2008). An influx of Kittlitz’s murrelets 

into Kenai Fjords during 2006 also was noted in nearby Kachemak Bay, whereas abundance was 

down in all three areas in 2007 compared to other years. The influx of Kittlitz’s murrelets in 

Kachemak Bay during 2006 was confined to the outer bay survey area and birds may have come 

from lower Cook Inlet populations (Kuletz and others, 2008). In Kenai Fjords, Kittlitz’s and 

marbled murrelets exhibited similar fluctuations in abundance between years, suggesting that 

interannual variability resulted from a common cause for both species. Because 2007 was an 

anomalous year for oceanographic conditions in the Gulf of Alaska (Janout and others, 2010), it is 

possible that regional oceanography played a role in low abundance of murrelets during midseason surveys during that year. The ultimate cause of this variability is unknown, but may 

possibly arise from fluctuations in breeding effort (when many birds do not breed and remain 

offshore), pulses of recruiting birds from previously successful years of reproduction, or pulses of 

sub-adult birds prospecting near breeding grounds (see below). 

20 
Within-season density patterns differed by species. When monthly densities were averaged 

over the three years of the study, Kittlitz’s murrelets increased in density from June to July, 

followed by a decline in density by early to mid-August. For marbled murrelets, average densities 

increased slowly from June to July and increased dramatically by late season counts in early to 

mid August. This suggests that post breeding dispersal occurred earlier in the season for Kittlitz’s 

murrelets, and presumably began by mid July. For marbled murrelets, abundance was highest in 

August and similar to late season density peaks in other areas (Speckman and others, 2000; 

Romano and others, 2004). Late season increases in marbled murrelets were likely due to variable 

subadult attendance and may be related to the strength of subadult cohorts and food availability 

(Speckman and others, 2000). 

Telemetry 

A likely Kittlitz’s murrelet nest was located in Northwestern Lagoon during 2006 by radio 

telemetry. The signal was located in an area that would be difficult (though not impossible) to 

reach due to cliffs and the persistence of snow blocking the route early in the season. The site 

where the signal was tracked had large, snow free patches on May 30 (N 59.77063°; W 

149.89635°). Relocation effort of radio-tagged birds suggest Kittlitz’s murrelets showed high site 

fidelity within Kenai Fjords; all birds were relocated within 10 km of their capture location in the 

upper fjord areas of Aialik Bay and Northwestern Lagoon. This is comparable to relocation 

distance for tagged Kittlitz’s murrelets in Glacier Bay (Romano and others, 2007b) and satellite 

tagged birds in Icy Bay and Kachemak Bay (J. Piatt, unpublished data, 2009). 

Productivity 

Very few fledgling Brachyramphus murrelets, particularly Kittlitz’s murrelets, were 

observed over the course of this study despite our effort to survey during what should have been 

the peak fledging period in south-central Alaska (Kuletz and Piatt, 1999; Kuletz and others, 2008). 

Similar efforts in Prince William Sound and Glacier Bay also were unsuccessful in finding many 

juvenile Kittlitz’s murrelets at sea (Day and Nigro, 2004, M. Romano, U.S. Geological Survey, 

oral commun., 2007). In contrast, the number of Kittlitz’s murrelet juveniles peaked in Kachemak 

Bay during mid-August and rapidly declined shortly thereafter (Kuletz and others, 2008). The low 

number of juvenile Kittlitz’s murrelets sighted in Kenai Fjords may indicate low breeding success 

and productivity during the course of this study. Alternatively, the absence of Kittlitz’s murrelets 

during August surveys may reflect the possibility that Kittlitz’s murrelet fledglings leave the 

coastal area immediately and that the timing of our coastal surveys provided a very short window 

of opportunity for sighting. 

We have no way of knowing how many non-breeding adults were present during 

productivity surveys, and these numbers would tend to deflate estimates of productivity. Low 

productivity indices also may reflect survey effort that missed the peak fledging period, 

particularly in 2007, when we observed an apparently late spring bloom and late fledgling period 

as suggested by the high number of birds holding fish (an indication of chick rearing) during midAugust surveys. 

21 
Habitat 

Oceanography 

Meso-scale (25 km in this study) patterns of phytoplankton production may influence 

interannual variability in local attendance of murrelets at sea, and this may explain the high 

interannual variability in mid-season counts. Within-season variability in Kittlitz’s murrelet 

density differed in 2007 compared to other years. The highest density of Kittlitz's murrelets 

occurred late in 2007, which suggests a delay in the onset of breeding during that year. Sampling 

along the Gulf of Alaska shelf adjacent to Kenai Fjords suggests 2007 was an anomalous year 

(Janout and others, 2010). Spring and summer temperature and salinity profiles fell outside the 

long-term average standard deviations in May, with cooler temperatures throughout the water 

column, fresher water at depth, and more saline water near the surface (Janout and others, 2010. 

Seasonal fluctuations in chlorophyll a and nutrient dynamics during summer 2008 suggest 

that the mechanisms governing these ecosystem components differ between fjords. Low 

chlorophyll a concentrations in glacial areas compared to distal areas of Aialik Bay indicated that 

chlorophyll a production in glacial areas is more influenced by shelf waters, which likely is 

because of the orientation of the mouth of Aialik Bay relative to the Alaska Coastal Current. 

Chlorophyll a patterns were more consistent and sustained in Northwestern Lagoon throughout the 

2008 summer, with relatively high chlorophyll a concentrations in glacial areas in June and July. 

Northwestern Lagoon is more enclosed with a more narrow passage and shallow sill, which 

inhibits exchange with more oceanic waters in distal areas (Gay and Armato, 1999). Our results in 

Northwestern Lagoon are in accordance with similar findings in Glacier Bay, Alaska, another 

enclosed and silled fjord that experiences high and sustained chlorophyll a concentrations, 

particularly in areas of intermediate stratification (Etherington and others, 2007). 

Our data were in accordance with the hypothesis that a water clarity profile characterized 

by high turbidity near the surface and clearer water below is important to Kittlitz’s murrelets 

feeding in glacial-marine environments (Kuletz and others, 2008). Low water clarity as a result of 

glacial runoff in Kenai Fjords generally was constrained to the surface layer (5–9 m) near 

tidewater glaciers. The water column below the turbid freshwater lens was clearer, and this 

physical feature is common in Kittlitz’s murrelet foraging habitat elsewhere (Barron and Barron, 

2005; Kuletz and others, 2008). Low water clarity was detected throughout the water column near 

Aialik Glacier in July, however, indicating higher subsurface sediment outflow as glacial melt 

increased throughout the summer warming period. This effect was very localized (less than 1 km 

from glacier) as subsurface beam transmission reached 80 percent at 12-m depth at a station 

sampled 2.3 km from the glacier. 

22 
Prey Availability 

The near-surface availability of euphausiids in the turbid waters near glacial stream 

outflows provided a prey resource for Kittlitz’s murrelets, and may have influenced their at-sea 

distribution. Euphausiids are an important prey type in Kittlitz’s murrelet diets (Sanger, 1987; 

Hobson and others, 1994; Day and others, 1999), comprising as much as 44 percent of Kittlitz’s 

murrelet and 31 percent of marbled murrelet diets in Alaska (Hobson and others, 1994). 

Weslawski and others (2000), who also found euphausiids were most abundant in the surface 

waters near glaciers, suggest that macrozooplankton are entrapped in inner fjord basins by 

physical processes, such as estuarine circulation. In addition to physical processes, euphausiid 

distribution is maintained by behavior, in particular, diel migration in response to light and also 

their relatively strong swimming abilities (Zhou and others, 2005). 

Although there are several explanations for the occurrence of euphausiids in surface waters 

near glaciers, including reproductive behavior, net avoidance in clear water, or subsurface 

upwelling, we believe that once entrained into glacial areas, near surface euphausiids were likely 

influenced by turbid glacial outflow that inhibited a photic cue for diel vertical migration. 

Euphausiids swarm to reproduce in surface waters during daylight hours (Hanamura and others, 

1989) and timing of surveys in Kenai Fjords overlapped with the reproductive period of 

euphausiids in nearby Prince William Sound and along the Gulf of Alaska Shelf (Pinchuk and 

others, 2008). However, the most abundant species collected within Kenai Fjords was T. inermis, 

which usually reproduces between April and May (Pinchuk and others, 2008) and earlier than our 

sampling commenced. Euphausiids collected in Northwestern Lagoon in July 2007 (this study) 

had spawned previously but were not actively reproducing at the time of capture (samples verified 

by A. Pinchuk, University of Alaska Fairbanks). Alternatively, it is possible that net avoidance in 

clear water explains the higher abundance of euphausiid catches in turbid water (Ken Coyle, 

University of Alaska Fairbanks, oral commun., 2008). We believe this was not the case, however, 

because trawl catches in Glacier Bay, using a net large enough (mouth opening of 50 m2

) to rule 

out net avoidance by organisms as small as euphausiids, showed a similar pattern of high daytime 

euphausiid abundance in surface waters nearest the glaciers (Robards and others, 2003). 

Subsurface glacial outflow can cause local upwelling, or “brown zones,” near the face of 

tidewater glaciers that bring biomass to the surface and can be an important physical structuring 

mechanism for zooplankton (Hartley and Dunbar, 1938); however, some tidewater glaciers in 

Kenai Fjords were grounded at low tide during this study. Observations of tidal velocity do not 

support the hypothesis that zooplankton are brought to the surface by upwelling because of 

subsurface freshwater flow from tidewater glaciers in Kenai Fjords, although this may be the case 

in other fjords (Day and others, 2003). Vertical velocities were not distinguishable in the current 

measurements from the front of the Aialik Glacier face because of the low overall current 

velocities relative to boat speed. In contrast, vertical velocities indicating upwelling and complex 

currents were detected in ADCP cross sections made at the sills. This is a key structural feature 

that induces mixing of inner fjord waters with Gulf of Alaska waters, and is a possible mechanism 

for bringing macrozooplankton into glacial areas (Carpenter, 1983). 

23 
Other marine organisms that typically occur at deeper depths during the day have been 

documented in surface waters near glaciers. Carpenter (1983) found that shrimp and other 

zooplankton were abundant throughout the water column near the face of Aialik Glacier; however, 

these crustaceans were collected only in deeper water during the day at the marine sill just 10 km 

away. This vertical distribution of shrimp near the glacier face was attributed to reduced light 

conditions due to turbid glacial outflow. Abookire and others (2002) also speculated that low light 

conditions explained the daytime presence of mesopelagic fishes in the turbid surface waters in 

Glacier Bay. Our data, along with similar observations of other studies, lend support to the 

hypothesis that the daytime, near-surface occurrence of marine organisms that typically undergo 

diel migrations may be because of the lack of a photic cue beneath turbid glacial outflows. 

Monthly acoustic biomass measurements in Kenai Fjords during 2008 indicated lower prey 

availability in June compared to later in the summer, and this was most likely a lagged response to 

marine production in the fjords. Patterns of acoustic biomass differed between fjords, with 

biomass in Northwestern Lagoon generally decreasing with distance from tidewater glaciers 

throughout the summer. Higher abundance of weak-scattering organisms, such as zooplankton in 

the upper 40 m near the head of Northwestern Lagoon, was a driver of this relationship. The 

relationship between acoustic biomass and glacial distance in Aialik Bay was more variable over 

the summer, with a significant positive response in the early season, and no significant 

relationship later in the season. In the middle and late summer, however, dense forage fish schools 

had clearly moved into glacial areas of Aialik Bay (fig. 19), a pattern that is consistent with studies 

elsewhere (Robards and others, 1999). These observations suggest forage fish abundance lags the 

peak in lower trophic level production. 

Nearshore habitats provide food resources, cover, and nursery habitat for forage fishes, and 

beach seining has proven an efficient way to sample fishes important in murrelet diets in these 

areas (Johnson and Thedinga, 2005). We documented the occurrence of important murrelet forage 

species including Pacific herring, Pacific sand lance, capelin, and surf smelt with beach seines in 

2007 and 2008. We also observed a large group of Kittlitz’s murrelets feeding (capturing and 

swallowing at the surface) on Pacific sand lance adjacent to a large kelp bed near the McCarty 

Glacier sill in the East Arm of Nuka Bay, where sand lance were frequently caught in beach 

seines. 

Glacial fjords in Alaska provide important spawning habitat and nursery areas for capelin 

during the spring and summer (Brown, 2002; Arimitsu and others, 2008). In Glacier Bay, a glacial 

fjord in southeast Alaska, the spawn timing for capelin was protracted, with spatial and temporal 

variation in maturation of ripe females (Arimitsu and others, 2008). In Kenai Fjords, spawning 

capelin were found in Pederson Lagoon, and larval capelin used Northwestern Lagoon as a 

nursery area. We found evidence that the capelin spawning period was synchronous in Kenai 

Fjords during 2008. Larval capelin were an order of magnitude more abundant in trawl catches 

during July than they were in June and August, and there was little variation in length frequency 

(table 9). This suggests that capelin spawning dynamics in Kenai Fjords differed from Glacier 

Bay, and also suggests that capelin can provide predictable forage resources for murrelets and 

other piscivorous marine birds in Kenai Fjords. 

24 
25 

Concurrent hydroacoustic and bird survey data indicated that Kittlitz’s murrelets utilized 

lower density forage fish aggregations and zooplankton that occur in the turbid glacial plume near 

tidewater glaciers. Low-density and dispersed prey was characteristic of prey availability for 

murrelets and other seabirds also in Prince William Sound (Ostrand and others, 1998, 2004). 

Although dense forage fish schools moved into the inner fjords by August 2008, earlier in the 

season, the area closest to tidewater glaciers contained weak-scattering organisms, such as 

zooplankton and low-density fish schools. Higher turbidity near glaciers may sustain low density 

or dispersed prey because (1) the lack of a photic cue inhibits vertical migration for zooplankton 

and fish, and (2) visual cues that aid in dense schooling behavior are suppressed in very turbid 

water (Partridge and Pitcher, 1980). 

In Kenai Fjords, interannual variability in murrelet population estimates was high, and 

marine habitat preferences differed by species. Low population estimates were coincident with 

anomalous marine conditions in 2007, which may reflect the influence of meso-scale 

oceanographic conditions on the timing of nesting phenology (inferred from at-sea density). As in 

previous studies (Day and Nigro, 2000; Day and others, 2000), Kittlitz’s murrelets were strongly 

associated with marine conditions found in waters adjacent to tidewater glaciers. This habitat was 

characterized by cool, sediment-laden glacial melt water where low light penetration limits 

phytoplankton abundance but also may enhance the availability of suitable prey near the surface. 

Dense forage fish schools moved into glacial areas over the course of the summer. In contrast, 

marbled murrelets were more associated with shallow water and tended to avoid ice in glacial 

areas, and they apparently had a wider tolerance to the range of marine habitat characteristics 

found within Kenai Fjords National Park. 

Acknowledgments 

This project was funded by the U.S. Geological Survey, including funds from the Alaska 

Science Center, and funds from the Natural Resource Protection Program, which is dedicated to 

research needs of the National Park Service. Funding to help support the late-season surveys for 

fledglings was provided by the Alaska Coastal Marine Resources Grant Program of the National 

Park Foundation. This project would not have been possible without the support of Naomi 

Bargmann, Camille Castaneda, Karl Deutsch, Gary Drew, Gavin McMorrow, Stuart Meyers, 

Aileen Miller, Andrew Ramey, Julie Schram, Greg Snedgen, Indu Soini, Shiway Wang, and Jon 

Wetzel. The staff of Kenai Fjords National Park, including Shelley Hall, Mark Kansteiner, Meg 

Hahr, Caroline Jezierski, Dan Shultz, and the captain and crew of the M/V Serac provided 

valuable assistance and support to this project. Chris Stark (UAF) analyzed zooplankton samples, 

and Kathy Krogslund (UW) analyzed nutrients samples. We also thank Bill Thompson (NPS), 

Deb Nigro (BLM), Dan Mulcahy (USGS), Kathy Kuletz (USFWS) Nicola Hillgruber (UAF), 

Terry Quinn (UAF), Franz Mueter (UAF), and Chris Hay-Jahans (UAS), who provided assistance 

during the planning and analysis phases of the study.
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Figure 1. Map showing Kenai Fjords study area showing place names used in this report. Marine sills are shown in yellow. 

30 
Figure 2. Map showing marine bird transect locations in Kenai Fjords National Park, Alaska, summers 

2006–08. Population estimates for Kittlitz's and marbled murrelets were derived from mid-season surveys 

(red, black, and dashed lines). A subset of transects (black lines) was surveyed in the early and 

late/fledgling seasons each year, and transects in the East Arm of Nuka Bay (dashed lines) were not 

surveyed during all sampling periods because of poor weather. 

31 
Figure 3. Map showing fledgling survey lines in Aialik Bay and Northwestern Lagoon, Alaska, 2007. Blue 

stipple represents ice extent and a black arrow indicates a survey within Pederson Lagoon. 

32 
Figure 4. Map showing approximate area (blue) covered by boat-based and aerial relocation surveys for 

radio-marked Kittlitz’s murrelets in the lower Kenai Peninsula area, May 10–July 1, 2006. Red circles 

indicate capture locations, and a black star indicates a possible nest site. 

33 
Figure 5. Map showing beach seine (triangles), oceanography stations (squares), and large Isaacs-Kidd 

Midwater Trawl (IKMT, red circles) stations sampled in Kenai Fjords, Alaska. Open squares indicate 

conductivity-temperature-depth (CTD) stations in the East Arm of Nuka Bay that were sampled in 2007 

only, and yellow squares were sampled in 2007 and 2008. CTD casts and water samples also were 

collected at IKMT stations. 

34 
Figure 6. Map showing large Isaacs-Kidd midwater trawl locations (red circles and black crosses), and 

euphausiid density (#/m3) during sampling, Kenai Fjords, Alaska, June 29–July 3, 2007. Bathymetric 

features are indicated in blue, with darker shades denoting deeper bottom depth. Ice extent is indicated by 

blue stipple. 

35 
36 

Figure 7. Map showing strata used to generate population estimates for Kittlitz’s and marbled murrelets, 

Kenai Fjords National Park, Alaska, 2006–08. 
Figure 8. Maps showing Kittlitz’s murrelet distribution during mid-season coastwide surveys, Kenai Fjords, 

Alaska. Transect lines are indicated by black lines and glacial extent is in blue stipple. 

 37
Figure 9. Maps showing Marbled murrelet distribution during mid-season coastwide surveys, Kenai Fjords, 

Alaska. Transects are indicated by black lines, and glacial extent is in blue stipple. 

 38
Figure 10. Maps showing Kittlitz’s murrelet (KIMU) and marbled murrelet (MAMU) distribution, including 

adult and juvenile records, during fledging period surveys in Northwestern Fjord and Aialik Bay, Kenai Fjords, 

Alaska. 

 39
 40

Figure 11. Maps showing location of radio-marked Kittlitz’s murrelets (circles) tracked by boat-based and 

aerial telemetry searches, and capture locations (squares), Kenai Fjords, Alaska, 2006. Top and bottom 

panels represent different birds. Star symbols indicate mortalities.
Figure 12. Graphs showing temperature (color) and salinity (line) vertical contours relative to bottom depth (m, x-axis) and g

Northwestern Fjord (two left panels) and Aialik Bay (two right panels), Alaska. Bathymetric features are indicated in solid blac 41 
Figure 13. Chlorophyll a vertical contours relative to depth (m, y-axis), and distance to tidewater glacier (km, 

x-axis) in Kenai Fjords National Park, Alaska. Photic depth is indicated as black diamonds, and position of 

the sill is indicated in solid black. 

42 
Figure 14. Water clarity vertical contours (beam transmission, %) relative to depth (m, y-axis) and distance 

to tidewater glaciers (km, x-axis), Kenai Fjords National Park, Alaska. Bathymetric features are indicated in 

black. 

43 
Figure 15. Graphs showing monthly average (SD) dissolved inorganic nitrogen (DIN, μM), nitrogen to 

phosphate ratio (N:P), and silicic acid (SiOH4, μM) values in Aialik Bay and Northwestern Fjord, Alaska, 

2008. 

44 
Figure 16. Graph showing backscatter vertical profile (color, decibels, dB) measured by an acoustic 

Doppler current profiler and salinity data measured at the front of Aialik Glacier, Alaska, August 14, 2007. 

The left side of the graph represents the south side of the fjord. 

45 
Figure 17. Graphs showing proportion of Isaacs-Kidd midwater trawl catches that were comprised of 

gelatinous zooplankton (GZ) relative to distance to nearest tidewater glacier in Aialik Bay (upper) and 

Northwestern Lagoon (lower), Alaska, 2008. The approximate location of the marine sills are indicated as a 

vertical grey dotted line.

46 
47 

Figure 18. Maps showing monthly hydroacoustic backscatter (nautical area scattering coefficient, NASC) 

due to dense forage schools and weaker scattering nekton measured in Kenai Fjords, Alaska, 2008. 
Figure 19. Graphs showing monthly relationship between acoustic backscatter and transect distance to tidewater glaciers in 

(top panel) and Aialik Bay (bottom panel), Kenai Fjords National Park, Alaska, 2008. 

48 
Table 1. Summary of at-sea survey effort in Kenai Fjords National Park, Alaska, 

during summers of 2006–08. 

[km2

, square kilometer; km, kilometer] 

Year Survey Survey dates 

Number 

of 

transects Survey 

area (km2) 

Survey 

length 

(km) 

2006 

Early 

Season 5/31–6/2 36 25.64 128.2 

Coastwide 

(midseason) 6/27–7/5 100 78.54 392.7 

Late Season 7/31–8/1 and 8/13 25 18.74 93.7 

 Fledgling 8/12 and 8/14 13 9.9 49.5 

2007 

Early 

Season 6/1–6/8 33 23.38 116.9 

Coastwide 

(midseason) 6/25–6/29 90 72.94 364.7 

Late Season 7/31–8/4 37 24.58 122.9 

 Fledgling 8/9–8/17 21 51.3 256.5 

2008 

Early 

Season 6/4–6/8 25 17.54 87.7 

Coastwide 

(midseason) 7/5–7/15 99 74.44 372.2 

 Late Season 8/7–8/10 27 19 95.0 

49 
Table 2. Summary of mid-season, coastwide surveys conducted in Kenai Fjords 

National Park, Alaska, during summers of 2006–08. 

[km2

, square kilometer; km, kilometer; %, percent] 

Stratum 

Distance 

surveyed (km) 

Number 

of 

transects 

Area 

surveyed 

(km2) 

Area of 

stratum 

(km2) 

Proportion 

sampled (%) 

Fjords Coastal 45.6 12 9.1 29.6 30.8 

Coastline 191.4 45 38.3 161.3 23.7 

Fjords Offshore 42.1 15 8.4 103.0 8.2 

Bays Offshore 113.7 28 22.7 320.6 7.1 

2006 Total 392.8 100 78.6 614.5 12.8 

Fjords Coastal 39.5 11 7.9 29.6 26.7 

Coastline 186.2 40 37.24 161.3 23.1 

Fjords Offshore 43.4 17 8.68 103 8.4 

Bays Offshore 95.6 22 19.12 320.6 6.0 

2007 Total 364.7 90 72.94 614.5 11.9 

Fjords Coastal 42.5 11 8.5 29.6 28.7 

Coastline 203.9 49 40.78 161.3 25.3 

Fjords Offshore 36.8 15 7.36 103 7.1 

Bays Offshore 88.9 24 17.78 320.6 5.5 

2008 Total 372.1 99 74.4 614.5 12.1 

50 
Table 3. Population estimates (95%-confidence intervals) and coefficients of variation (%) for Brachyramphus murrelets in K

Park, Alaska, 2006–08. [Species abbreviations are Kittlitz's murrelet (KIMU), marbled murrelet (MAMU), and all Brachyramphus murre

(BRMU). Total estimates are based on the sum of line transect estimates for birds sighted on the water and strip tbirds sighted in the air. Detection probabilities for line transect estimates were modeled using observations of all 

within 100 meters of the survey vessel] 

KIMU MAMU BRMU 

Year Behavior N (95% CI) CV N (95% CI) CV N (95% CI) 

2006 Water 740 (268–2,042) 55.7 6,082 (4,416–8,376) 16.4 6,930 (4,737–10,136) 

Fly 185 (63–539) 67.6 336 (184–614) 31.5 656 (409–1,052) 

Adjusted Estimate 925 (393–2,179) 45.9 6,418 (4,730–8,709) 15.6 7,586 (5,344–10,768) 

2007 Water 407 (239–694) 27.8 3,460 (2,228–5,373) 22.7 4,224 (2,915–6,121) 

Fly 16 (4–61) 77.4 159 (59–367) 44.7 200 (99–402) 

Adjusted Estimate 423 (252–709) 26.8 3,619 (2,371–5,524) 21.8 4,424 (3,099–6,315) 

2008 Water 664 (294–1,499) 43.4 7,441 (5,463–10,136) 15.9 9,290 (7,086–12,180) 

Fly 0 0 88 (32–240) 54.7 387 (196–763) 

Adjusted Estimate 664 (294–1,499) 43.4 7,529 (5,546–10,222) 15.7 9,677 (7,449–12,571) 

51 
Table 4. Proportion (percent) of Brachyramphus murrelets (all behaviors, and flying birds only) that were 

Kittlitz's murrelets (KIMU), marbled murrelets (MAMU), and unidentified Brachyramphus 

Murrelets (UNMU) observed within 100 meters of the vessel during Kenai Fjords surveys, 

Alaska, 2006–08. 

 Observations of all murrelets Observations of flying murrelets 

Year Survey 

period KIMU MAMU UNMU KIMU MAMU UNMU 

2006 Early 23.4 74.9 1.8 4.2 2.1 60.0 

Middle 14.6 83.8 1.6 19.8 4.7 60.0 

Late 3.6 93.7 2.7 0.0 0.9 82.4 

2007 Early 10.7 85.7 3.6 0.0 1.8 37.5 

Middle 11.7 78.9 9.4 5.4 2.8 10.8 

Late 3.5 93.0 3.5 2.6 3.9 18.3 

2008 Early 13.5 82.8 3.7 2.4 2.0 35.7 

Middle 14.3 79.5 6.2 0.0 0.6 14.0 

Late 2.6 93.3 4.0 0.0 0.7 25.0 

52 
53 

Table 5. Within season density estimates (D, birds/km2), confidence intervals (CI), 

and coefficients of variation (CV, %) for Kittlitz's murrelets (KIMU), marbled 

murrelets (MAMU) in Kenai Fjords National Park, Alaska, 2006–08. 

[Estimates were derived from the raw counts and counts that were prorated for 

unidentified birds by transect. km2

, square kilometer] 

KIMU MAMU 

Year 

Survey 

period D (95% CI) CV D (95% CI) CV 

2006 Early 2.34 (0.99–4.04) 34.2 12.16 (8.14 – 16.48) 18.1 

Middle 3.67 (0.28–9.19) 64.8 16.12 (8.28–26.87) 29.6 

Late 0.74 (0.17–1.45) 44.2 24.09 (15.44–33.87) 20.3 

2007 Early 3.26 (1.08–5.91) 39.9 19.11 (12.72–26.70) 19.2 

Middle 1.40 (0.32–2.97) 49.0 12.63 (6.90–19.66) 24.8 

Late 1.81 (0.82–3.29) 34.4 47.88 (34.44–65.12) 16.3 

2008 Early 2.61 (1.04–4.40) 32.6 9.98 (5.31–15.61) 26.1 

Middle 2.94 (0.99–5.95) 42.4 18.40 (12.54–25.30) 18.0 

 Late 0.76 (0.15–1.69) 54.6 29.68 (18.60–45.13) 21.9 

 Prorated KIMU Prorated MAMU 

2006 Early 2.44 (1.08–4.43) 34.4 12.26 (8.59–17.11) 18.5 

Middle 3.67 (0.23–9.66) 67.7 16.16 (8.54–26.34) 28.8 

Late 0.74 (0.18–1.52) 44.6 24.31 (16.12–36.11) 20.7 

2007 Early 3.56 (1.13–6.53) 38.4 20.41 (13.76–29.61) 20.1 

Middle 1.55 (0.43–3.23) 46.9 12.77 (7.57–19.34) 23.6 

Late 2.05 (0.91–3.66) 35.3 50.81 (35.49–68.34) 16.6 

2008 Early 2.73 (1.12–4.66) 33.2 10.33 (5.81–15.53) 24.7 

Middle 3.33 (1.08–6.14) 40.0 20.45 (13.84–28.06) 18.5 

 Late 0.76 (0.17–1.81) 53.5 30.80 (19.93–45.73) 20.9 
Table 6. Average density (SE) within strata across years for Kittlitz's 

murrelets (KIMU), marbled murrelets (MAMU), and all Brachyramphus 

murrelets combined (BRMU) during mid-season coastwide surveys in 

Kenai Fjords, Alaska, 2006–08. 

Stratum KIMU MAMU BRMU 

Bays coastal 0.02 (0.01) 13.19 (4.36) 14.49 (5.30) 

Bays Offshore 0.02 (0.02) 6.39 (1.60) 7.15 (1.85) 

Fjord Offshore 5.97 (1.58) 9.16 (3.12) 16.73 (3.74) 

Fjord Coastal 1.61 (1.05) 25.32 (4.00) 30.15 (3.28) 

Table 7. Kittlitz’s murrelet measurements from May 2006 in Kenai Fjords 

compared to May 2004 in Glacier Bay, Alaska. 

[g, gram; mm, millimeter; asterisk*, p < 0.05] 

Data source 

Body 

mass 

(g) 

Tarsus 

(mm) 

Wing 

chord 

(mm) 

Culmen 

(mm) 

2006 Kenai Fjords Mean 222.3 18.2 140.9 10.7 

N=8 Std Err 6.2* 0.2 1.2 0.2 

2004 Glacier Bay Mean 238.9 17.6 139.4 11.1 

N=20 Std Err 4.3* 0.2 1 0.3 

Table 8. Nutrient concentrations (μM) sampled in Northwestern Lagoon and Aialik Bay, Alaska, 2008. 

[SE, standard error; m, meters; μM, micro moles per liter] 

 Surface 10 m

Nutrient Range Mean SE Range Mean SE 

Phosphate 0.140–0.870 0.368 0.035 0.210–0.900 0.519 0.044 

Silicic Acid 1.980–9.270 4.439 0.362 2.620–8.420 5.557 0.34 

Nitrate 0–5.190 0.512 0.215 0.070–4.800 1.446 0.329 

Nitrite 0–0.120 0.03 0.006 0–0.150 0.054 0.011 

Ammonium 0.010–4.920 0.776 0.224 0.010–3.510 1.131 0.209 

54 
Table 9. Species, size (fork length, mm), and sample size (n) of fishes captured in small and large IsaacsKidd midwater trawls (IKMT), Kenai Fjords, Alaska, 2007–08. 

[SD, standard deviation; n, sample size] 

 Small IKMT Large IKMT 

Common Name Scientific Name Size Range (n) Average (SD) 

Size 

Range (n) Average (SD) 

Pacific herring Clupea pallasii – – 14–22 (5) 17 (3.1) 

Northern smoothtongue Leuroglossus schmidti 27 (1) 27 – – 

Capelin Mallotus villosus – – 5–30 (845) 14 (5.3) 

Eulachon Thaleichthys pacificus 26 (1) 26 – – 

Larval smelt Osmeridae (Family) 26 (1) 26 14 (1) 14 

Lanternfish Myctophidae (Family) – – 15 (1) 15 

Saffron cod Eleginus gracilis 12–51 (97) 31 (9.8) 7–69 (55) 24 (19.1) 

Walleye pollock Theragra chalcogramma 17–41 (86) 25 (4.5) 7–16 (24) 10 (2.7) 

Pacific cod Gadus macrocephalus 33–36 (2) 35 (2.1) 12 (1) 12 

Gadid Gadidae (Family) 12–32 (32) 22 (5.2) – – 

Rockfish Sebastes spp. 11–19 (6) 14 (3.2) – – 

Spinyhead sculpin Dasycottus setiger 12–25 (142) 14 (3.2) 25–30 (31) 28 (1.4) 

Padded sculpin Artedius fenestralis – – 14 (1) 14 

Sculpin Cottidae (family) – – 7–12 (4) 10 (2.2) 

Soft sculpin Psychrolutes sigalutes 12–54 (4) 34 (19.0) 35–48 (2) 42 (9.2) 

Crested sculpin Blepsias bilobus 21–27 (5) 24 (2.2) – – 

Silverspotted sculpin Blepsias cirrhosus – – 13 (1) 13 

Northern ronquil Ronquilus jordani 30 (1) 30 12–43 (3) 25 (16.3) 

Snailfish Liparidae (family) 13–19 (9) 15 (2.2) 12–18 (4) 16 (3.2) 

Poacher Agonidae (family) 8–20 (19) 16 (3.5) 10–18 (4) 14 (4.3) 

Sturgeon poacher Podothecus accipenserinus 20 (1) 20 – – 

Daubed shanny Leptoclinus maculatus 28–45 (4) 37 (6.9) – – 

Snake prickleback Lumpenus sagitta 22–67 (15) 45 (17.1) 23–47 (22) 37 (9.5) 

Longsnout prickleback Lumpenella longirostris – – 50 (1) 50 

Lumpenus sp. Lumpenus spp. 23 (2) 23 (0) – – 

Larval prickleback Sticheaidae (Family) 21–63 (19) 41 (15.5) 26 (1) 26 

Quillfish Ptilichthys goodei – – 173 (1) 173 

Prowfish Zaprora silenus 26–36 (4) 31 (4.8) 25 (1) 25 

Pacific sandfish Trichodon trichodon 57 (1) 57 – – 

Pacific sand lance Ammodytes hexapterus 23–43 (5) 30 (7.9) 16–28 (2) 22 (8.5) 

Flathead sole Hippoglossoides elassodon 12–25 17) 20 (3.1) 9–38 (224) 21 (5.5) 

Butter sole Isopsetta isolepis 18–25 (8) 21 (2.4) – – 

Northern rock sole Lepidopsetta polyxystra 15–21 (6) 18 (2.4) 12–17 (3) 15 (2.5) 

Sand sole Psettichthys melanosticus 13–21 (4) 16 (3.6) 10 (1) 10 

Rock Sole (unidentified) Lepidopsetta spp. 13–22 (3) 16 (4.9) – – 

Larval flatfish Pleuronectidae (Family) 12–24 (23) 19 (3.5) – – 

55 
Table 10. Results from 3-way fixed effects permutation-based MANOVA 

under the null hypothesis that there was no difference in Bray Curtis 

similarity index of Kittlitz's murrelet zooplankton prey species in 

glacial versus distal stations (glacial), Aialik versus 

Northwestern (fjord), or time period (month). 

Source SS MS Pseudo-F P 

Glacial 1,517.6 1,517.6 1.3477 0.218 

Fjord 2,698.3 2,698.3 2.3962 0.029 

Month 8,160.7 8,160.7 7.2469 0.003 

Residual 13,513 1,126.1 

Total 25,890 

56 
Table 11. Species, size (fork length, mm), and sample size (n) of nearshore fishes captured with a beach 

seine in Kenai Fjords, Alaska, 2007–08. 

[SD, standard deviation; n, sample size] 

Common name Scientific name Size range (n) Average (SD) 

Pacific herring Clupea pallasii 30–143 (155) 98 (20.9) 

Capelin Mallotus villosus 105 (1) 105 

surf smelt Hypomesus pretiosus 37–145 (62) 87 (32.8) 

Chum salmon Oncorhynchus keta 39–69 (96) 59 (7.6) 

Pink salmon Oncorhynchus gorbuscha 32–134 (636) 87 (21.1) 

Sockeye Oncorhynchus nerka 59–104 (46) 84 (12.7) 

Dolly varden char Salvelinus malma 150–202 (3) 184 (29.5) 

Silver Salmon Oncorhynchus kisutch 149 (1) 149 

Pacific cod Gadus macrocephalus 50–95 (86) 64 (8.3) 

Threespine stickleback Gasterosteus aculeatus 29 (1) 29 

greenling Hexagrammos sp. 28 (1) 28 

Rock greenling Hexagrammos lagocephalus 140 (1) 140 

White-spotted greenling Hexagrammos stelleri 64–82 (15) 71 (4.5) 

Sculpin Cottidae (family) 12–15 (2) 14 (2.1) 

Padded sculpin Artedius fenestralis 34 (1) 34 

Buffalo sculpin Enophrys bison 45–119 (7) 78 (23.0) 

Great sculpin Myoxocephalus polyacanthocephalus 32–159 (5) 68 (51.3) 

sharpnose sculpin Clinocottus acuticeps 17–27 (2) 22 (7.1) 

Myox sp. Myoxocephalus sp. 12–20 (21) 17 (2.3) 

Eelpout Lycodapus sp. 37 (1) 37 

Daubed shanny Lumpenus maculatus 61 (1) 61 

Crescent gunnel Pholis laeta 39 (1) 39 

Pacific sand lance Ammodytes hexapterus 32–156 (1757) 97 (33.9) 

Yellowfin sole Pleuronectes asper 45 (1) 45 

57 
58 

Table 12. Parameter estimates for best-fit model using generalized linear-mixed 

models to relate Kittlitz’s and marbled murrelet presence/absence (binomial response) 

to marine habitat variables measured in Kenai Fjords National Park, Alaska, 

July 2008. 

[Acoustic backscatter was log-transformed, and all continuous variables were 

normalized prior to analysis to allow direct comparison of coefficients. The 

coefficient for fjord reflects the difference in mean probability of occurrence 

between fjords at the logit scale] 

Kittlitz's murrelet (400-m segment lengths) 

 Coefficient SE t p 

Intercept -8.7408 1.8674 -4.68 < 0.001 

Bathymetry 1.7453 0.5563 3.14 < 0.01 

Acoustic 1.8992 0.5461 3.48 < 0.001 

Glacial Distance -6.0131 1.3055 -4.61 < 0.001 

Fjord (Aialik = 1) 6.9365 1.9259 3.6 < 0.01 

Marbled murrelet (800-m segment lengths) 

 Coefficient SE t p 

Intercept 0.6718 0.377 1.78 0.0779 

Bathymetry -0.3268 0.2414 -1.35 0.179 

Ice -1.4687 0.5425 -2.71 < 0.01 
Appendix 1. Total Count of All Birds and Marine Mammals Observed on Early Season Su

Fjords, Alaska, 2006–08. [Species are arranged in taxonomic order] 

Order Family Common name Scientific name Code 2

Gaviiformes Gaviidae Common Loon Gavia immer COLO 

Pacific Loon Gavia pacifica PALO Red-throated Loon Gavia stellata RTLO Red-necked Grebe Podiceps grisegena RNGR 

Pelecaniformes Phalacrocoracidae Double-crested Cormorant Phalacrocorax auritus DCCO 

Pelagic Cormorant Phalacrocorax pelagicus PECO Red-faced Cormorant Phalacrocorax urile RFCO Unidentified Cormorant Phalacrocorax spp. UNCO 

Anseriformes Anatidae Mallard Anas platyrhychos MALL 

Harlequin Duck Histrionicus histrionicus HADU Surf scoter Melanitta perspicillata SUSC White-winged Scoter Melanitta fusca WWSC Barrow's Goldeneye Bucephala islandica BAGO Common Merganser Mergus merganser COME Red-breasted Merganser Mergus serrator RBME Greater Scaup Aythya marila GRSC Unidentified Duck UNDU 

Falconiformes Accipitridae Bald Eagle 

Haliaeetus leucocephalus BAEA 

59 
Appendix 1. Total Count of All Birds and Marine Mammals Observed on Early Season Su

Fjords, Alaska, 2006–08.—Continued 

Order Family Common name Scientific name Code 2

Charadriiformes Haematopodidae Black Oystercatcher Haematopus bachmani BLOY 

Scolopacidae Black Turnstone Arenaria melanocephala BLTU 

Red-necked Phalarope Phalaropus lobatus RNPH 

Laridae Parasitic Jaeger Stercorarius parasiticus PAJA 

Pomarine Jaeger Stercorarius pomarinus POJA Mew Gull Larus canus MEGU Glaucous-winged Gull Larus glaucescens GWGU 1Herring Gull Larus argentatus HEGU Black-legged Kittiwake Rissa tridactyla BLKI Arctic Tern Sterna paradisaea ARTE 

Alcidae Common Murre Uria aalge COMU 

Pigeon Guillemot Cepphus columba PIGU marbled murrelet 

Brachyramphus marmoratus MAMU 2

Kittlitz's murrelet 

Brachyramphus brevirostris KIMU 

Unidentified Brachyramphus murrelet Brachyramphus spp. BRMU Rhinoceros Auklet Cerorhinca monocerata RHAU Horned Puffin Fratercula corniculata HOPU 

Passeriformes Corvidae Common Raven Corvus corax CORA 

Northwestern Crow Corvus caurinus NOCR 

Carnivora Mustelidae Sea Otter Enhydra lutris SEOT 

Mustelidae River Otter Lutra canadensis RIOT Otariidae Steller Sea Lion Eumetopias jubatus STSL Phocidae Harbor Seal Phoca vitulina HASE Urcidae Black Bear Ursus americanus BLBE 

Cetacea (Mysticeti) Balaenopteridae Humpback Whale Megaptera novaeangliae HUWH 

60 
Appendix 2. Total Count of All Birds and Marine Mammals Observed on Mid-Season Sur

Fjords, Alaska, 2006–08. 

[Species are arranged in taxonomic order] 

Order Family Scientific name Common name Species Code 2006 

Gaviiformes Gaviidae Gavia immer Common Loon COLO 1 

Gavia sp. Unidentified Loon UNLO 0 

Puffinus griseus Sooty Shearwater SOSH 1 

Pelecaniformes Phalacrocoracidae Phalacrocorax auritus Double-crested Cormorant DCCO 238 

Phalacrocorax urile Red-faced Cormorant RFCO 25 Phalacrocorax pelagicus Pelagic Cormorant PECO 298 Phalacrocorax sp. Unidentified Cormorant UNCO 70 

Anseriformes Anatidae Branta bernicla Brant BRAN 0 

Branta canadensis Canada Goose CAGO 0 Anas crecca Green-winged Teal GRTE 0 Histrionicus histrionicus Harlequin Duck HADU 96 Melanitta perspicillata Surf Scoter SUSC 64 Melanitta fusca White-winged Scoter WWSC 32 Mergus merganser Common Merganser COME 99 Mergus serrator Red-breasted Merganser RBME 0 

Falconiformes Accipitridae Haliaeetus leucocephalus Bald Eagle BAEA 50 

61 
Appendix 2. Total Count of All Birds and Marine Mammals Observed on Mid-Season Sur

Fjords, Alaska, 2006–08.—Continued 

Order Family Scientific name Common name Species Code 2006 

Charadriiformes Haematopodidae Haematopus bachmani Black Oystercatcher BLOY 13 

Scolopacidae Arenaria melanocephala Black Turnstone BLTU 0 Laridae Phalaropus fulicaria Red Phalarope RNPH 0 

Larus canus Mew Gull MEGU 45 Larus glaucescens Glaucous-winged Gull GWGU 4,751 Larus argentatus Herring Gull HEGU 6 Rissa tridactyla Black-legged Kittiwake BLKI 1,126 

Alcidae Uria aalge Common Murre COMU 162 

Uria sp. Unidentified Murre UNMU 0 Cepphus columba Pigeon Guillemot PIGU 292 Synthiliboramphus antiquus Ancient murrelet ANMU 2 Brachyramphus marmoratus marbled murrelet MAMU 857 

Brachyramphus brevirostris Kittlitz's murrelet KIMU 81 Brachyramphus sp. 

Unidentified Brachyramphus

murrelet BRMU 27 

Cerorhinca monocerata Rhinoceros Auklet RHAU 262 Fratercula corniculata Horned Puffin HOPU 397 Fratercula cirrhata Tufted Puffin TUPU 214 

Passeriformes Corvidae Corvus caurinus Northwestern Crow NOCR 0 

Carnivora Mustelidae Enhydra lutris Sea Otter SEOT 123 

Mustelidae Lutra canadensis River Otter RIOT 0 Otariidae Eumetopias jubatus Steller Sea Lion STSL 33 Phocidae Phoca vitulina Harbor Seal HASE 146 Urcidae Ursus Americanus Black Bear BLBE 1 

Cetacea (Mysticeti) Balaenopteridae Megaptera novaeangliae Humpback Whale HUWH 1 

Cetacea (Odontoceti) Phocoenidae Phocoenoides dalli Dall's Porpoise DAPO 0 

62 
Appendix 3. Total Count of Birds and Marine Mammals Observed on Late-Season Survey

Alaska, 2006–08. [Species are arranged in taxonomic order] 

Order Family Scientific name Common name Species 2006 

Pelecaniformes Phalacrocoracidae Phalacrocorax auritus Double-crested Cormorant DCCO 18 

Phalacrocorax pelagicus Pelagic Cormorant PECO 9 

Phalacrocorax urile Red-faced Cormorant RFCO 1 Phalacrocorax spp. Unidentified Cormorant UNCO 0 

Anseriformes Anatidae Histrionicus histrionicus Harlequin Duck HADU 51 

Anas platyrhychos Mallard MALL 3 Melanitta perspicillata Surf Scoter SUSC 12 Melanitta fusca White-winged Scoter WWSC 0 Melanitta spp. Unidentified Scoter UNSC 0 

Mergus serrator Red_breasted Merganser RBME 35 Mergus merganser Common Merganser COME 0 

Unidentified Duck UNDU 0 

Falconiformes Accipitridae Haliaeetus leucocephalus Bald Eagle BAEA 2 Charadriiformes Haematopodidae Haematopus bachmani Black Oystercatcher BLOY 3 

Scolopacidae Arenaria melanocephala Black Turnstone BLTU 0 

Phalaropus lobatus Red-necked Phalarope RNPH 0 

63 
64 

Appendix 3. Total Count of Birds and Marine Mammals Observed on Late-Season SurveyAlaska, 2006–08.—Continued 

Order Family Scientific name Common name Species 2006 

Charadriiformes Laridae Stercorarius pomarinus Pomarine Jaeger POJA 0 

Larus canus Mew Gull MEGU 1 

Larus glaucescens Glaucous-winged Gull GWGU 295 Rissa tridactyla Black-legged Kittiwake BLKI 121 Sterna paradisaea Arctic Tern ARTE 5 

Alcidae Uria aalge Common Murre COMU 52 

Uria lomvia Thick-billed Murre TBMU 0 Cepphus columba Pigeon Guillemot PIGU 30 Synthliboramphus antiquus Ancient murrelet ANMU 0 Brachyramphus marmoratus marbled murrelet MAMU 345 Brachyramphus brevirostris Kittlitz's murrelet KIMU 13 Brachyramphus spp. 

Unidentified Brachyramphus

murrelet BRMU 17 

Cerorhinca monocerata Rhinoceros Auklet RHAU 30 Fratercula corniculata Horned Puffin HOPU 20 Fratercula cirrhata Tufted Puffin TUPU 45 

Passeriformes Corvidae Corvus caurinus Northwestern Crow NOCR 0 

Carnivora Mustelidae Enhydra lutris Sea Otter SEOT 19 

Phocidae Phoca vitulina Harbor Seal HASE 225 Urcidae Ursus americanus Black Bear BLBE 0 

Cetacea (Mysticeti) Balaenopteridae 

Megaptera novaeangliae Humpback Whale HUWH 0 
Appendix 4. Catch Per Unit Effort (CPUE, # m-3) and Frequency of 

Occurrence (FO) of Small Zooplankton at Stations Sampled with a Ring 

Net, Kenai Fjords, Alaska, 2007. 

[Species are arranged in order of relative abundance. Sample size, 21; SD, standard deviation] 

Taxon Species 

Mean 

CPUE SD FO 

Copepod Pseudocalanus spp. 25,741.64 15,582.57 1 

Copepod Oithona similis 6,363.39 274.79 1 

Copepod Acartia longiremis 27,28.71 2,597.47 1 

Copepod Calanus marshallae 161.26 187.96 1 

Chaetognath Sagitta elegans 69.82 67.26 1 

Gastropod Limacina helicina 22.48 241.12 1 

Gastropod Gastropod larvae 233.66 488.64 0.96 

Larvacean Oikopleura sp. 14.83 97.84 0.96 

Copepod Metridia pacifica 128.27 125.35 0.92 

Copepod Centropages abdominalis 81.33 8.55 0.88 

Copepod Eucalanus bungii 25.94 27.75 0.79 

Decapod Hippolytidae zoea 3.38 3.97 0.75 

Bivalve Bivalvia 135.22 277.17 0.71 

Euphausiid Euphausiid (nauplii-juvenile) 8.19 12.94 0.71 

Copepod Neocalanus flemingeri 4.25 5.14 0.71 

Decapod Paguridae zoea 2.52 2.86 0.71 

Cladoceran Evadnae 286.52 147.25 0.58 

Hydrozoan Bougainvilla sp 0.34 0.47 0.5 

Copepod Neocalanus plumchrus 1.72 2.54 0.46 

Copepod Copepoda nauplii 251.86 685.72 0.42 

Decapod Pisinae zoea 1.23 2.14 0.42 

Decapod Brachyrhancha zoea 2.78 6.29 0.29 

Decapod Pinnotheridae zoea 0.47 1.22 0.29 

Copepod Oncea 36.29 89.55 0.25 

Cnidarian Aglantha digitale 0.28 0.62 0.25 

Barnacle Cirripedia 23.9 76.86 0.21 

Polychaete Polychaete 10 32.51 0.21 

Copepod Harpacticoida 7.34 27.71 0.21 

Cnidarian Anthomedusae 2.85 7.19 0.21 

Cnidarian Coryne princeps 0.3 0.79 0.21 

Copepod Neocalanus cristatus 0.18 0.47 0.21 

Cnidarian Leptomedusae 0.11 0.28 0.21 

Nemertea Nemertina 6.16 27.67 0.17 

Isopod Cryptoniscidae 2.66 7.17 0.17 

Amphipod Parathemisto sp. 0.89 2.89 0.17 

Decapod Pandalus sp. 0.61 0.14 0.17 

Decapod Pandalidae zoea 0.46 1.44 0.17 

Gastropod Clione limacina 0.24 0.76 0.17 

Copepod Microcalanus sp. 11.17 42.5 0.13 

Mysiid Mysidacea 0.62 0.23 0.08 

Copepod Epilabedocera amphitrites 0.41 1.41 0.08 

65 
Appendix 4. Catch Per Unit Effort (CPUE, # m-3) and 

Frequency of Occurrence (FO) of Small Zooplankton at 

Stations Sampled with a Ring Net, Kenai Fjords, Alaska, 

2007.—Continued 

Taxon Species 

Mean 

CPUE SD FO 

Cnidarian Rathkea 0.23 0.81 0.08 

Hydrozoan Lars flavicirratus 0.12 0.44 0.08 

Copepod Scolethricella minor 4.53 22.17 0.04 

Copepod Oithona spinirostra 1.13 5.54 0.04 

Euphausiid Thysanoessa raschii 0.88 0.43 0.04 

Amphipod Parathemisto libellula 0.88 0.43 0.04 

Cladocrean Podon 0.47 2.4 0.04 

Gastropod Echinospira 0.47 2.4 0.04 

Copepod Calanus pacificus 0.35 1.73 0.04 

Decapod Oregoninae zoea 0.35 0.17 0.04 

Polychaete Syllidae 0.35 0.17 0.04 

Decapod Crangonidae zoea 0.22 0.18 0.04 

Ostracod Conchoceia sp. 0.18 0.87 0.04 

Euphausiid Euphausia pacifica 0.18 0.87 0.04 

Siphonophore Siphonophore Bract 0.18 0.87 0.04 

66 
Appendix 5. Catch Per Unit Effort (CPUE, # m-3) and Frequency of 

Occurrence (FO) of Small Zooplankton at Stations Sampled with a 

Ring Net, Kenai Fjords, Alaska, 2008. 

[Species are arranged in order of relative abundance. Sample size, 24. SD, standard 

deviation] 

Taxon Species Mean CPUE SD FO 

Copepod Pseudocalanus spp. 128,853.33 73,987.36 1.00 

Copepod Oithona similis 35,232.00 16,493.34 1.00 

Copepod Acartia longiremis 16,586.67 12,195.59 0.96 

Euphausiid Euphausiid (nauplii-juvenile) 1,937.42 2,855.71 0.96 

Copepod Calanus marshallae 692.83 1,051.33 0.96 

Chaetognath Sagitta elegans 284.46 343.62 0.92 

Gastropod Limacina helicina 900.83 1,212.42 0.83 

Copepod Eucalanus bungii 60.50 114.67 0.79 

Copepod Metridia pacifica 1,258.67 1,568.50 0.75 

Gastropod Gastropod larvae 1,074.67 1,198.22 0.75 

Larvacean Oikopleura sp. 825.33 1,033.35 0.71 

Copepod Neocalanus plumchrus 421.50 763.74 0.67 

Copepod Copepoda nauplii 3,424.00 4,937.44 0.63 

Copepod Centropages abdominalis 371.33 838.52 0.58 

Decapod Hippolytidae zoea 10.50 16.29 0.54 

Bivalve Bivalvia 1,241.33 2,842.61 0.46 

Polychaete Polychaete 433.33 726.04 0.46 

Amphipod Parathemisto sp. 15.17 28.75 0.46 

Barnacle Cirripedia 321.33 482.50 0.42 

Gastropod Echinospira 233.33 668.41 0.38 

Cnidarian Eirene indicans 6.04 14.53 0.33 

Cladoceran Evadnae 234.00 671.57 0.29 

Decapod Paguridae zoea 4.33 8.74 0.29 

Cnidarian Aglantha digitale 4.00 10.20 0.29 

Cladoceran Podon 19.33 47.88 0.21 

Decapod Pisinae zoea 2.83 7.69 0.17 

Decapod Brachyrhancha zoea 2.00 6.67 0.17 

Larvacean Fritillaria sp. 192.00 581.08 0.13 

Echinoderm Echinodermata 108.00 426.18 0.13 

Isopod Cryptoniscidae 106.67 301.17 0.13 

Copepod Neocalanus flemingeri 8.42 39.14 0.13 

Cnidarian Coryne princeps 0.54 1.79 0.13 

Copepod Epilabedocera amphitrites 0.25 0.68 0.13 

Copepod Harpacticoida 86.67 417.81 0.08 

Copepod Oncea 24.00 104.76 0.08 

Bryzoan Bryozoa cyphonautes 24.00 104.76 0.08 

Copepod Acartia tumida 6.67 26.66 0.08 

67 
68 

Appendix 5. Catch Per Unit Effort (CPUE, # m-3) and Frequency of 

Occurrence (FO) of Small Zooplankton at Stations Sampled with a 

Ring Net, Kenai Fjords, Alaska, 2008.—Continued 

Taxon Species Mean CPUE SD FO 

Cnidarian Rathkea 6.33 26.37 0.08 

Hydrozoan Bougainvilla sp 1.17 4.93 0.08 

Copepod Neocalanus cristatus 0.50 1.79 0.08 

Amphipod Cyphocaris challengeri 0.38 1.64 0.08 

Cnidarian Perigonimus sp. 0.38 1.64 0.08 

Echinoderm Echinodermata "pleutes" 42.67 209.02 0.04 

Copepod Oithona spinirostra 2.67 13.06 0.04 

Copepod Metridia ochatensis 1.83 8.98 0.04 

Fish Fish (sm) 1.00 4.90 0.04 

Copepod Calanus pacificus 0.33 1.63 0.04 

Fish Plueronectidae 0.33 1.63 0.04 

Amphipod Parathemisto libellula 0.25 1.22 0.04 

Decapod Pandalus platyceros 0.17 0.82 0.04 

Decapod Oregoninae zoea 0.17 0.82 0.04 

Amphipod Hyperoche meduserum 0.08 0.41 0.04 

Hydrozoan Lars flavicirratus 0.08 0.41 0.04 

Decapod Pandalopsis dispar 0.04 0.20 0.04 

Euphausiid Thysanoessa inremis 0.04 0.20 0.04 

Euphausiid Euphausia pacifica 0.04 0.20 0.04 
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For more information concerning the research in this report, contact the 

Director, Alaska Science Center

U.S. Geological Survey

4210 University Dr.

Anchorage, Alaska 99508-4650

http://alaska.usgs.gov
Arimitsu and others— Kittlitz’s and Marbled Murrelets in Kenai Fjords National Park, South-Central Alaska: At-Sea Distribution, Abundance, and Foraging Habitat, 2006–08—Open-File Report 2010–1181