Characterizing Risk Associated with Vessel Fouling and Non‐

indigenous Species in Prince William Sound

Jeffery Cordell and Elizabeth Sosik  

School of Aquatic and Fishery Science; University of Washington

and

Maurya Faulkner and Chris Scianni

California State Lands Commission

Prepared for the Prince William Sound Regional Citizensʹ Advisory Council

October 30, 2009 
2

Table of contents 

Table of contents ................................................................................................................................................................. 2

Figures .................................................................................................................................................................................... 4

Tables ...................................................................................................................................................................................... 5

Appendix Tables ................................................................................................................................................................. 5

Executive Summary .......................................................................................................................................................... 6

Introduction ....................................................................................................................................................................... 12

Shipping Data .................................................................................................................................................................... 14

Methods ............................................................................................................................................................................ 14

Data Categories ................................................................................................................................................................ 15

Results .................................................................................................................................................................................. 16

All ports combined ......................................................................................................................................................... 16

Ship arrivals by year. ...................................................................................................................................................... 16

Voyage types by year...................................................................................................................................................... 16

Voyage histories ............................................................................................................................................................. 17

Duration of time in port .................................................................................................................................................. 19

By port .............................................................................................................................................................................. 20

Ship arrivals by year and port. ....................................................................................................................................... 20

Ship types by port........................................................................................................................................................... 21

Voyage types by port ...................................................................................................................................................... 23

Voyage histories by port ................................................................................................................................................. 23

Voyage histories by vessel type ................................................................................................................................... 24

Number of arrivals by year............................................................................................................................................. 24

Number of repeat visits by vessel type. .......................................................................................................................... 25

Duration of time in port .................................................................................................................................................. 26

Voyage types by vessel type ........................................................................................................................................... 28

Voyage history by vessel type ........................................................................................................................................ 29

Conclusions ...................................................................................................................................................................... 30

Risk based on visitation patterns (time in port vs frequency) ........................................................................................ 31

Risk based on port .......................................................................................................................................................... 33

Hull Maintenance ............................................................................................................................................................ 35

Hull Maintenance Overview ........................................................................................................................................ 35

Hull Maintenance Procedure ...................................................................................................................................... 37

Anti-Fouling Systems .................................................................................................................................................... 37

Hot Spots .......................................................................................................................................................................... 38

Other Risk Factors ........................................................................................................................................................ 39

Example Hull Maintenance Schedules ...................................................................................................................... 40

Hull fouling sampling methods and recommendations .................................................................................... 43
3

Introduction .................................................................................................................................................................... 43

Methods ............................................................................................................................................................................ 43

Visual Rank Assessment ................................................................................................................................................ 43

Diving ............................................................................................................................................................................ 43

Dry Dock ........................................................................................................................................................................ 44

Archival Video Footage ................................................................................................................................................. 44

ROV ............................................................................................................................................................................... 45

Pros and Cons ................................................................................................................................................................. 47

Cost ................................................................................................................................................................................ 47

Representativeness ......................................................................................................................................................... 47

Data Type and Quality .................................................................................................................................................... 47

Assessment of ROV and Diver Sampling ................................................................................................................. 49

ROV ............................................................................................................................................................................... 49

Diver Surveys ................................................................................................................................................................. 50

Recommendations .......................................................................................................................................................... 51

Level one—Archived video ........................................................................................................................................... 52

Level two—ROV and diver video surveys .................................................................................................................... 53

Level three—targeted biological sampling by divers ..................................................................................................... 53

References ........................................................................................................................................................................... 55
4

Figures 

Figure 1. Total vessel arrivals per year to Alaska ports of interest 2005-2008. ..................................... 16 

Figure 2. Number of voyage types per year to Alaska ports of interest 2005-2008. . ............................ 17 

Figure 3. Voyage history of all arrivals per year to Alaska ports of interest 2005-2008. . ..................... 18 

Figure 4. Voyage histories of vessels entering Alaskan ports of interest from the Pacific northwest 

United States and British Columbia 2005-2008. . .......................................................................... 18 

Figure 5. Voyage histories of vessels entering Alaskan ports of interest from Asia 2005-2008. ........... 19 

Figure 6. Duration in port of all vessel arrivals to Alaskan ports of interest, 2005-2008. ...................... 20 

Figure 7. Total arrivals to each port of interest per year, 2005-2008. .................................................... 21 

Figure 8. Percent composition of vessel traffic to Alaskan ports of interest, 2005-2008. ...................... 22 

Figure 9. Percent composition of voyage types for vessels entering Alaskan ports of interest, 2005-

2008. . .............................................................................................................................................. 23 

Figure 10. Percent composition of voyage histories for vessels entering Alaskan ports of interest, 2005-

2008. . .............................................................................................................................................. 24 

Figure 11. The total arrivals of each vessel type per year for vessels entering Alaskan ports of interest, 

2005-2008. ...................................................................................................................................... 25 

Figure 12. The number of arrivals of each vessel type staying in port more than 72 hours, for vessels 

entering Alaskan ports of interest, 2005-2008. ............................................................................... 28 

Figure 13. Percent composition of voyage types by vessel type, for vessels entering Alaskan ports of 

interest, 2005-2008. ........................................................................................................................ 29 

Figure 14. Percent composition of voyage histories by vessel type, for vessels entering Alaskan ports of 

interest, 2005-2008. ....................................................................................................................... 30 
5

Tables

Table 1. Average number of each vessel type per year arriving to Alaskan ports of interest, 2005-2008.

 ......................................................................................................................................................... 22 

Table 2. Average and maximum number of visits to Alaskan ports of interest 2005-2008 by vessel type.

 ......................................................................................................................................................... 26 

Table 3. Duration in port (hours) of arrivals to Alaskan ports of interest 2005-2008 by vessel type. .... 27 

Table 4. Average number of each voyage type by vessel type, for arrivals to Alaskan ports of interest 

2005-2008.. ..................................................................................................................................... 28 

Table 5. Average numbers of each voyage history type for arrivals to Alaskan ports of interest 2005-

2008 by vessel type.. ....................................................................................................................... 30 

Table 6. Hull maintenance of tank ships operating in Alaskan ports of interest .................................... 42 

Table 7. Hull fouling studies and methods ............................................................................................. 46 

Appendix Tables 

Appendix Table 1. Voyage histories of vessels entering Alaskan ports of interest, 2005-2008. NW = 

Pacific northwest of United States + British Columbia, SF = San Francisco Bay area, S. CA = 

southern California. ......................................................................................................................... 60 

Appendix Table 2. Number of arrivals to Alaskan ports of interest 2005-2008 by vessel type. ............ 61 

Appendix Table 3. Voyage types of arrivals by port, 2005-2008, for vessels entering Alaskan ports of 

interest, 2005-2008. ........................................................................................................................ 62 

Appendix Table 4. Voyage types of incoming arrivals by vessel type, 2005-2008, for vessels entering 

Alaskan ports of interest, 2005-2008. ............................................................................................. 63 

Appendix Table 5. Voyage history of incoming arrivals to Alaskan ports of interest 2005-2008 by 

vessel type. ...................................................................................................................................... 64 

Appendix Table 6. Distribution of fouling organisms outside their native ranges. ................................ 65 

Appendix Table 7. Anti-fouling paints used and hull locations where applied. ..................................... 68 
6

Executive Summary 

Little is known about the organisms associated with the hulls of ships entering the coastal waters of 

Alaska, but fouling biota on ship’s hulls elsewhere have been shown to be diverse and contain species 

that are not native to many of the regions visited by the ships. An initial step in assessing the potential 

risk of invasions by non-indigenous species (NIS) associated with ship’s hulls is to characterize vessel 

arrivals with regard to risk factors such as voyage history, time spent in port, vessel type, and the 

distribution and nature of shipping intensity among ports. Another information-gathering step is to 

summarize information about hull cleaning and maintenance practices of major vessel types that 

comprise potential vectors for NIS. This information can be used to evaluate the scale of risk of 

introductions by fouling organisms among vessel types, routes, and ports, and can help identify regions 

likely to contribute NIS. This approach can help to focus subsequent efforts targeting specific risk 

factors. Understanding hull fouling associated invasion risk ultimately requires measuring biota 

associated with hulls. This type of analysis can range from low resolution data gathered from archived 

hull maintenance video to comprehensive remote-operated vehicle or diver surveys (the latter can 

include physical samples of fouling communities), but costs for these kinds of analyses increase as the 

data quality and quantity increases. Thus, analyzing shipping patterns, hull maintenance practices, and 

the pros and cons of various hull fouling sampling methods can help prioritize how to focus more 

intensive and comprehensive sampling efforts. In this report, we examine these factors, with particular 

regard to Prince William Sound, Alaska. 

The overall goals of this project were as follows: 

• Evaluate 2005-2008 vessel arrival data for ports in Prince William Sound and the Ports of 

Kodiak and Seward (henceforth termed ports of interest). 

• Conduct an initial assessment of tankers traveling to Prince William Sound, by evaluating 

maintenance schedules and periodicity and location of hull cleaning. 

• Summarize the literature on hull fouling studies and hull sampling techniques. 

• Based on the results, evaluate and recommend sampling and analysis protocols that can be used 

in studies of hull fouling in the region. 

Shipping Patterns 

In order to evaluate shipping patterns, we obtained vessel arrival data from the US Coast Guard’s 

Shipping Arrival Notification System (SANS) for the years 2005-2008, for the ports of interest—Cape 

Hinchinbrook, College Fjord, Cordova, Kodiak, Prince William Sound (No port given), Seward, 
7

Tatitlek, Valdez, and Whittier. The data received included information on the port of arrival, date and 

time of arrival, vessel name, date and time of departure, previous ports visited, and the time of arrival 

to and departure from the previous ports. 

In addition to examining patterns of all vessel arrivals combined, arrival data for individual vessel visits 

were categorized by voyage type, vessel type, time spent in port, and voyage history. The main 

findings from the vessel arrival data were as follows: 

• Total vessel arrivals declined from 2005 to 2008, with the sharpest drop in 2006. 

• Most arrivals were tank and passenger vessels originating from the west coast, followed by 

domestic (within Alaska) and transpacific voyages. 

• The most commonly visited way-points on voyages were in the Puget Sound area and British 

Columbia, followed by the San Francisco Bay area and Southern California. 

• The majority of arrivals stayed in port for less than 24 hours, but there was a small subset of 

vessels that stayed in port more than 72 hours consisting mostly of tank ships (2005), passenger 

vessels (2006) and fishing boats (2007 and 2008). In each year, there was at least one arrival 

that stayed more than 72 hours for most of the vessel categories. 

• Valdez had the majority of arrivals, followed by much lower arrival numbers, in decreasing 

order at Whittier, Kodiak, Seward, Prince William Sound (No port given), Cordova, Cape 

Hinchinbrook, College Fjord, and Tatitlek. 

• Ports of interest with relatively high shipping activity had different patterns based on vessel 

types visiting: Valdez was dominated by tank ships, Whittier by passenger and towing vessels, 

Kodiak by fishing and freight vessels, and Seward by passenger vessels. 

• Ports with high shipping activity also varied by voyage type of arriving vessels: those arriving 

in Kodiak came mainly from within Alaska, while those arriving to Valdez, Whittier, and 

Seward were mostly from elsewhere on the west coast of North America. 

• Ports that had relatively high proportions of arrivals that had visited potential NIS “hot spots” 

in their voyage histories included Valdez, Cape Hinchinbrook (San Francisco Bay), Seward and 

Kodiak (Asia). 

• Ship types that had relatively high proportions of arrivals that had visited potential NIS “hot 
8

spots” in their voyage histories included tank ships (San Francisco Bay), passenger vessels and 

freight ships (Asia). 

The analysis identified two categories of vessels: those that have set routes and make numerous brief 

return trips to the same port, and those that return to port infrequently but stay in port for long periods 

of time. The first type presents a risk of repeat inoculations of NIS (potential high propagule 

frequency), and the second represents risk based on less frequent inoculations with longer “incubation” 

time for NIS to release propagules (potential high propagule volume). Tank ships and passenger vessels 

represent the high frequency risk category, while freight and fishing vessels represent the high volume 

risk category. 

Several ports probably have relatively higher risk of NIS being introduced from hull fouling. Valdez 

has the highest overall amount of vessel traffic, with relatively high numbers of vessels that had 

previously visited potential NIS “hot spots” in Puget Sound, San Francisco Bay, and Southern 

California. Whittier and Seward may be at risk from the high volume of passenger vessel and towing 

vessel traffic arriving from elsewhere on the Pacific coast of North America. Fouling organisms may 

have better survival rates on these vessel types due to relatively short voyages in coastal waters 

hospitable to the organisms. Towing vessels may also have higher survival rates because of slow 

average voyage speeds. A relatively large proportion of passenger vessels had stops in Mexico and 

Asia that may be sources of NIS, they operate in the summer months when propagule pressure may be 

high, and the high return rate of the vessels allows for potential repeat inoculations. 

Domestic freight ships and fishing boats may present a risk to the port of Kodiak from secondary 

invasion by already introduced NIS arriving from other Alaskan ports. Relatively long “residence time” 

of fishing boats and freight ships may allow for the accumulation and/or release of fouling organisms. 

Hull Maintenance 

Currently, there is little federal regulation regarding hull husbandry practices: vessels are only required 

to rinse anchors and anchor chains to remove organisms and remove fouling organisms from hull, 

piping, and tanks on a regular basis. However, the main ship type traveling to Prince William Sound 

waters, crude oil tankers engaged in coastwise trade, are exempt from these requirements. Tank ship 

companies conduct voluntary high pressure washing of hulls, usually in conjunction with dry dock 
9

inspections that are typically required every five years, but this cleaning is conducted for operational 

reasons, and fouling that does not interfere with ship operations may be allowed to persist. 

Several factors related to hull maintenance are important with regard to the risk of transporting fouling 

NIS, including time since last cleaning and re-painting, use of anti-fouling treatment systems, 

maintenance of “hot spots” such as sea chests, cleaning method, and where the ship has been since 

being cleaned. In order to collect preliminary data on these factors, we evaluated maintenance 

information from 18 of the 26 tank ships operating Prince William Sound from 2005 to 2008. This 

information was acquired by the California Marine Invasives Program at the California State Lands 

Commission (CSLC), from reporting forms submitted to the CSLC by ship operators. The data 

collected includes: 

1. Dates and location of last out of water maintenance. 

2. Date of last full or partial coat of anti-fouling paint application, type of biocide used, and 

locations of the hull where applied. 

3. Whether Marine Growth Protection Systems have been installed in the sea-chests. 

4. Dates of in water cleaning, if applicable. 

5. Whether the vessel has, since the last cleaning: recently visited freshwater or tropical areas, 

been through the Panama Canal, or stayed ten consecutive days in a single port. 

Of the 18 vessels, the greatest duration of time since last maintenance or build was five years, and the 

average time since last maintenance or build was two years. All of the shipping companies interviewed 

reported conducting hull cleanings with a high pressure wash on dry dock at least once every five 

years. 

Hull Fouling Sampling Methods and Recommendations 

Five techniques have been commonly used to sample biofouling on hulls: (1) evaluating archival video 

footage of under water in lieu of Drydock (UWILD) inspections; (2) conducting above-water visual 

rank assessment; (3) collecting specimens and photo quadrats immediately after a vessel has been 

drydocked; (4) using divers to collect specimens and conduct underwater photo quadrats; and (5) using 

remotely operated vehicles (ROVs) to conduct video transects. 
10

Inspection of archived maintenance videos can yield broad patterns of fouling across numerous ships, 

and is relatively inexpensive to process. On the down side, videos are usually taken near the end of a 

ship’s maintenance cycle, and thus may be biased toward the most highly fouled conditions, and most 

species cannot be identified in videos. Likewise, visual rank assessment, using a ranking of 0 to 5 for 

intensity of fouling, can yield large amounts of data at low expense, but yields biased data in that only 

small vessels and the parts of the hull visible from above the water can be assessed. 

Collecting data during scheduled dry-docking events is also a relatively inexpensive option, and could 

allow for collection of specimens for species-level identifications. However, because tank ships in the 

northeast Pacific usually drydock in Asia, costs would include travel to Asian drydock facilities that 

service the tank ships. As with videos, sampling drydocked vessels may also yield biased samples 

because they are at the end of a maintenance cycle, and access to a hull in drydock could be nonuniform: for example, if specimens could only be collected from areas accessible by ladder, the 

majority of the hull would not be characterized. 

The use of divers and ROVs are the most expensive options, but costs may be lowered if divers or an 

ROV are available within the institution conducting the sampling. Diver and ROV surveys can be 

conducted at any point in a vessel's maintenance schedule, and thus provide a more representative 

sampling regime. They can also be done on predetermined transects and/or “hot spots” of interest. 

ROVs can stay in the water indefinitely, while divers are time-limited. However, in addition to visual 

surveys, divers can collect quantitative samples of biota for species level identification, including 

focusing on observed “hot spots”. 

We recommend a three-level sampling strategy for evaluating hull fouling. The first level would utilize 

UWILD video footage from vessels arriving to Prince William Sound. If the videos contain enough 

footage to sufficiently cover vessel types and underwater surfaces, a set number of quadrats from still 

frames would be randomly examined on each hull, along with semi-random quadrats on non-hull “hot 

spot” surfaces. Taxa richness and percentage cover data would then be analyzed. If enough adequate 

footage is found, this level would yield information on the extent of biofouling across a large subset of 

vessels arriving to Prince William Sound, but would not provide information on specific NIS. If the 

data from archival footage supplies enough information to detect fouling patterns associated with 

vessel types, voyage types, etc., then studies may proceed to a smaller more focused level three study. 

If meaningful patterns cannot be detected due to limitations of the archived video, a level two study 
11

may be conducted. 

In a level two study, ROV or diver video surveys would be conducted that offer more ability to target 

ports, vessel types, or voyage types of interest, and specific areas on an individual hull. The control 

afforded by this method allows vessels to be directly compared in a uniform manner. Divers or ROVs 

would conduct several transects along the length of a vessel's hull, followed by special attention “hot 

spots”. A real-time video feed may also be viewed by biologists who could identify areas to be 

sampled. During post-processing of videos taken at this level, videos could be paused at both random 

points and targeted focal points to obtain percent cover and presence/absence of organisms at broad 

taxonomic levels. As with archived video, a level two study would not provide much species-level 

identification of potential NIS. 

Level three study would involve targeted biological sampling that could be conducted on vessels of 

interest. This sampling could also be done in conjunction with level two sampling, if it is conducted by 

divers. This method is the most costly and might best be conducted by strategically narrowing the 

subset of vessels to be sampled to those that are hypothesized to be high risk vectors, as determined by 

level one and two sampling. Divers would collect representative samples of fouling observed along 

transects on vessel hulls, and video or visual assessment could also be conducted. Transects could be 

saved as video files and analyzed extensively. Biological samples could be rapidly assessed while alive, 

but most species identifications would be done from samples that are fixed and sent to taxonomic 

experts. Level three sampling yields high resolution information on specific fouling organisms and 

potential and known NIS found in hull samples. Percent cover can also be obtained, though due to 

limitations in the time divers can spend in the water, this data may be limited to only portions of a 

vessel. 
12

Introduction 

Though little studied in comparison to ship’s ballast waters, fouling biota on ship’s hulls have been 

shown to be diverse and in some cases comprised of numerous species that are not native to many of 

the regions visited by the ships. For example, Drake and Lodge (2007) found that a single ship 

entering the Great Lakes from Algeria had 74 marine and freshwater taxa, at least eight of which had 

never been seen in the Great Lakes; hull fouling may be responsible for at least 75% of the shipmediated NIS in Port Philip Bay, Australia (Hewitt 2004); a recent sampling of biota scraped from hulls 

of commercial vessels in Germany showed NIS on 96% of the 131 ships examined (Gollasch 2002); a 

survey of 8 vessels in Hawaii found NIS on the hulls of a majority of the vessels, despite low levels of 

fouling (Godwin 2003); and a single inspection of a relatively clean passenger vessel in Australia found 

a number of NIS in protected areas of the ship, including the European green crab Carcinus maenus 

(Coutts et al 2003). A series of rapid assessment surveys in Washington, Oregon and California 

consistently found significant levels of invasive fouling organisms on docks, pilings and other intertidal 

structures (Cohen et al. 1998, 2001, 2002, 2005a, 2005b). Other papers, such as Davidson et al. (2006a) 

and Coutts and Taylor (2004), while not addressing specific NIS species assemblages, point out the 

biosecurity risks posed by hull fouling. 

Recent studies of ships as vectors of NIS in Alaska have focused on ballast water (Ruiz et al. 2000, 

McGee et al. 2006). Very little is known about the organisms associated with the hulls of ships entering 

the coastal waters of Alaska, though an examination by Ruiz et al. (2000) of the hulls of two tankers 

entering Valdez, Alaska, found a diverse fouling assemblage including one NIS mussel species on the 

vessel that had not been recently cleaned. An initial step in assessing the potential risk of invasions by 

NIS associated with ship’s hulls is to characterize ship arrivals with regard to risk factors such as 

voyage history, time spent in port, vessel type, and the distribution and nature of shipping intensity 

among ports. Another information-gathering step is to summarize information about hull cleaning and 

maintenance practices of major vessel types that comprise potential vectors for NIS. This information 

can be used to evaluate the scale of risk of introductions by fouling organisms among various vessel 

types, routes, and ports, and can help to identify the regions likely to contribute NIS. This approach 

can help to focus subsequent efforts that target specific risk factors. Understanding hull fouling 

associated invasion risk ultimately requires measuring biota associated with hulls. This type of analysis 

can range from low resolution data gathered from archived hull maintenance video to comprehensive 
13

remote-operated vehicle or diver surveys (the latter can include physical samples of fouling 

communities), but costs for these kinds of analyses increase greatly with increases in data quality and 

quantity. Thus, initial analyses of shipping patterns, hull maintenance practices, and the pros and cons 

of various hull fouling sampling methods can help prioritize how to focus more intensive and 

comprehensive sampling efforts. In this report, we examine these factors, with particular regard to 

Prince William Sound, Alaska. 

The overall goals of this project were as follows: 

• Evaluate 2005-2008 vessel arrival data for ports in Prince William Sound and the Ports of 

Kodiak and Seward (henceforth termed ports of interest). 

• Conduct an initial assessment of tankers traveling to Prince William Sound, by evaluating 

maintenance schedules and periodicity and location of hull cleaning. 

• Summarize the literature on hull fouling studies and hull sampling techniques, and related 

topics such as remote assays of organisms for other purposes. 

• Based on the results, evaluate and recommend sampling and analysis protocols that can be used 

in studies of hull fouling in the region. 
14

Shipping Data 

Methods 

The Ship Arrival Notification System (SANS) is a database that provides advance notice of arrival and 

departure information from vessels coming to port in the United States. Vessel Notice of Arrival 

Reports (NOA) that are compiled by SANS record information received from a vessel’s owner, 

operator, or agent relating to the arrival and departure of vessels. Data includes details about vessels, 

reporting party, arrival and departure times, voyage information, crew, passenger and cargo manifest, 

previous ports visited, and ship security and safety certifications. According to 33 CFR 160, certain 

vessels are required to submit NOAs to the National Vessel Movement Center (NVMC), operated by 

the US Coast Guard. All US and foreign vessels bound for or departing from ports or places the US 

must submit NOAs; however there are numerous exemptions. Vessels that are not required to submit 

NOAs include, but are not limited to: (1) US recreational vehicles; (2) passenger and supply vessels 

engaged in the exploration for or removal of oil, gas, or mineral resources on the continental shelf; (3) 

oil spill recovery vessels engaged in spill response operations or exercises; (4) vessels 300 gross tons or 

less, unless carrying dangerous cargo; (5) vessels operating exclusively within a Captain of the Port 

Zone, unless carrying dangerous cargo; (6) towing vessels and barges operating solely between ports or 

places within the continental US, unless carrying dangerous cargo; and (7) public vessels. Due to these 

exemptions, gaps in the data may exist and the SANS database should not be considered an exhaustive 

record of all shipping traffic. The SANS database is, however, the most extensive database available. 

Ship arrival data was obtained from the SANS for the years 2005-2008. We specifically requested data 

for the ports of Cape Hinchinbrook, College Fjord, Cordova, Kodiak, Prince William Sound (No port 

given), Seward, Tatitlek, Valdez and Whittier. These ports are henceforth referred to as the ports of 

interest. 

The raw data received included information on the port of arrival, date and time of arrival, vessel name, 

date and time of departure, previous ports visited, and the time of arrival to and departure from the 

previous ports. The data was processed to eliminate repeat entries, and to ensure that arrival and 

departure times were in logical sequence. 

Each entry was assigned one of the following voyage types: domestic, west coast, transpacific, other, 
15

west coast-domestic, transpacific-domestic and transpacific-west coast-domestic. Domestic voyages 

were those that had not reported visiting ports outside of Alaska. West coast voyages were those 

confined to the east Pacific. Transpacific voyages were those that had crossed a significant portion of 

the Pacific, including Asia, Australia, French Polynesia, and Hawaii. 'Other' voyages were those that 

did not fit into the other main categories, and included Europe, the Gulf of Mexico, and Africa. The 

multiple voyage type categories (west coast-domestic, transpacific domestic, and transpacific-west 

coast-domestic) were of special note, as the hulls of vessels from these types of voyages might have 

been exposed to a diverse array of potential fouling organisms. 

Each entry was also assigned a vessel category which included fishing boat, tank ship, freight ship, 

passenger vessel, towing vessel, and other. Freight ships included any type of cargo ship. The “other” 

category was used for any vessel that did not fit into the other main categories, and included 

recreational vessels, research vessels, and cable ships. 

A second database was created in which all previous port entries were tagged with a keyword. The 

keywords included Northwest (NW); British Columbia (BC); Puget Sound area (Puget); Oregon (OR); 

San Francisco Bay area (San Francisco); Mexico; South America; Central America; Pacific Islands and 

Australia (South Pacific); Asia; Japan; South Korea; Singapore; China; India; Russia; Malaysia; and 

Vietnam. 

Data Categories 

The data was arranged in a the following ways to highlight potential trends :

• total number of vessel arrivals per year. 

• total number of different voyage types for all arrivals per year. 

• voyage history of all arrivals per year. 

• duration of time in port for each arrival, per year. 

• total number of vessel arrivals per year, by port. 

• average number of each vessel type arriving to each port of interest. 

• average number of different voyage types for each port of interest. 

• average voyage history of all arrivals, by Port. 

• total number of vessel arrivals per year, by vessel type. 

• average number of repeat visits for each vessel type. 

• duration of time in port for each arrival of each vessel type, per year. 
16

• average number of different voyage types for each vessel type. 

• average voyage history of all arrivals, by vessel type. 

Results 

All ports combined 

Ship arrivals by year. 

The number of total vessel arrivals declined from 2005 to 2008, with the sharpest drop in 2006 (Figure 

1). 

0

100

200

300

400

500

600

700

800

900

2005 2006 2007 2008

Year

Arrivals

Figure 1. Total vessel arrivals per year to Alaska ports of interest 2005-2008. 

Voyage types by year 

The majority of incoming arrivals originated from the west coast. Domestic voyages were the next 

most common type of arrival, followed by transpacific voyages. Total west coast voyages (which 

include west coast-domestic voyages) decreased in 2006, and then stabilized. Total domestic voyages 

decreased in 2007 and stabilized in 2008. Total transpacific voyages (which include all multiple voyage 

types that had a transpacific component) did not change through the study period (Figure 2). 
17

0

100

200

300

400

500

600

700

Domestic Other Total Transp Total WC

Voyage Type

Arrivals

2005

2006

2007

2008

Figure 2. Number of voyage types per year to Alaska ports of interest 2005-2008. Domestic = voyages 

within Alaska, Transp = transpacific voyages, WC = voyages from the west coast of North America, 

excluding domestic voyages. 

Voyage histories 

The most commonly visited way-points on voyages were located in the Pacific Northwest region of the 

United States and British Columbia (PNW), with an average of 469 visits (Figure 3, Appendix Table 1). 

Within this region, the Puget Sound area was the most commonly visited with 253-390 visits per year, 

followed by British Columbia with 153-195 visits per year, and Oregon with 13-39 visits per year 

(Figure 4, Appendix Table 1). The San Francisco Bay area was the next most commonly visited region 

with an average of 165 visits, followed by Southern California with an average of 100 visits. There was 

little difference in the visit frequencies of the other four regions; Asia had an average of 34 visits, 

Mexico an average of 24 visits, the South Pacific an average of 19 visits and ‘other’ locations had an 

average of 13.5 visits (Figures 3, 5, Appendix Table 1). There was a general decline in waypoint visits 

over the study period to the Pacific Northwest, San Francisco, Southern California, and Asia regions, 

and a small increase in visits over the study period to the South Pacific, Mexico and ‘other’ regions 

(Figure 3, Appendix Table 1). 
18

0

200

400

600

800

Asia NW SF S.CA S. Pacific Other Mexico

Voyage Waypoints

Arrivals

2005

2006

2007

2008

Figure 3. Voyage history of all arrivals per year to Alaska ports of interest 2005-2008. NW = Pacific 

northwest of United States + British Columbia, SF = San Francisco Bay area, S. CA = southern 

California. 

0

50

100

150

200

250

300

350

400

450

OR Puget BC

Voyage Waypoints

Arrivals

2005

2006

2007

2008

Figure 4. Voyage histories of vessels entering Alaskan ports of interest from the Pacific northwest 

United States and British Columbia 2005-2008. OR = Oregon, Puget = Puget Sound, Washington, BC = 

British Columbia. 
19

0

5

10

15

20

25

Japan South Korea China Russia Malaysia India Singapore Vietnam

Voyage Waypoints

Arrivals

2005

2006

2007

2008

Figure 5. Voyage histories of vessels entering Alaskan ports of interest from Asia 2005-2008. 

Duration of time in port 

The majority of arrivals stayed in port for less than 24 hours (455-572 arrivals per year). The number of 

vessels in port for 24-48 hours was much lower (44-131 arrivals per year) and the lowest number of 

vessels were in port for 48-72 hours (9-25 arrivals). There was a small increase in the number of 

arrivals staying in port for longer than 72 hours (30-39 arrivals). There was a general decrease over the 

course of the study period in number of vessels staying in port for 0-24, 24-48, and 48-72 hours, while 

the numbers of vessels in the >72 hour category was similar among years. The sharpest decreases 

occurred in 2006 (Figure 6) 
20

0

100

200

300

400

500

600

700

0-24 24-48 48-72 >72

Duration of time in port (hours)

Arrivals

2005

2006

2007

2008

Figure 6. Duration in port of all vessel arrivals to Alaskan ports of interest, 2005-2008.

By port 

Ship arrivals by year and port. 

Valdez had the majority of arrivals from 2005-2008 (299-414 arrivals, average = 335.75 per year), 

followed by much lower arrival numbers at Whittier (87-122 arrivals, average = 103.5 per year), 

Kodiak (75-138 arrivals, average = 97.5 per year), and Seward (64-81 arrivals, average = 72.75 per 

year) (Figure 7). Ports of interest with the lowest arrival rates were: Prince William Sound (11-16 

arrivals, average = 13.25 per year), Cordova (4-12 arrivals, average = 7.25 per year), Cape 

Hinchinbrook (1-16 arrivals, average = 5.75 per year), College Fjord (0-16 arrivals, average = 4.25 per 

year) and Tatilek (0-6 arrivals, average = 1.5 per year). There was a general decrease in arrivals over 

the course of the study in the ports of Valdez, Kodiak and Whittier. The majority of this drop occurred 

in 2006, with Valdez experiencing the largest decrease in arrivals (Appendix Table 2). 
21

0

50

100

150

200

250

300

350

400

450

Cape Hinchinbrook

College Fjord

Cordova

Kodiak

Prince William Sound

Seward

Valdez

Whittier

Tatilek

Port Name

Number of arrivals

2005

2006

2007

2008

Figure 7. Total arrivals to each port of interest per year, 2005-2008. 

Ship types by port 

Tank ships comprised the greatest proportion of arrivals on average in Valdez (94.7% of the total), 

which represented 96.7% of total tank ship arrivals (Table 1, Figure 8). Whittier’s arrivals on average 

were almost exclusively passenger vessels and towing vessels (63.0% and 35.0% of Whittier traffic, 

respectively) which represented 45.0% of total passenger vessel arrivals and 65.9% of total towing 

vessel arrivals. The largest proportion of arrivals to Kodiak were freight ships, followed by fishing 

boats (53.6% and 27.4% of Kodiak traffic, respectively), which represented 79.5% of the total freight 

ship arrivals and 63.3% of fishing boat arrivals. Seward’s traffic was mainly composed of passenger 

vessels (77.3% of Seward traffic), which represented 38.8% of total passenger vessel arrivals. (See 

Appendix Table 2 for yearly counts). 
Table 1. Average number of each vessel type per year arriving to Alaskan ports of interest, 2005-2008. 

Ship Type Cape Hinchinbrook College Fjord Cordova Kodiak PWS Seward Valdez Whittier Tatilek Fishing 0.0 0.0 3.0 26.8 5.8 3.3 2.3 1.3 0.0 Freight 0.0 0.0 0.3 52.3 2.0 7.5 3.3 0.5 0.0 Passenger 0.0 4.3 2.0 10.3 0.5 56.3 5.0 65.3 1.5 Tank 5.8 0.0 0.0 0.0 4.8 0.3 318.0 0.3 0.0 Towing 0.0 0.0 1.8 6.0 0.0 3.8 7.3 36.3 0.0 Other 0.0 0.0 0.3 2.3 0.3 1.8 0.0 0.0 0.0 Grand Total 5.8 4.3 7.3 97.5 13.3 72.8 335.8 103.5 1.5 

0%

10%20%30%40%50%60%70%80%90%

100%

Cape Hinchinbrook College Fjord CordovaKodiak Prince William SoundSewardValdezWhittierTatilek Port

Arrivals

OtheTowinTankPasseFreigFishin

Figure 8. Percent composition of vessel traffic to Alaskan ports of interest, 2005-2008. 
23

Voyage types by port 

Total west coast voyages (combining west coast and west coast-domestic voyages) accounted for the 

majority of arrivals in Valdez, Whittier, Seward, Prince William Sound (No port given), College Fjord, 

Cape Hinchinbrook and Tatilek. Cordova and Kodiak were the only two ports where domestic voyages 

accounted for the majority of arrivals. Total transpacific voyages arrived mainly to (in order of 

prevalence) the ports of Valdez, Seward, Whittier and Kodiak (Figure 9). (See Appendix Table 3 for 

yearly counts). 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Cape Hinchinbrook

College Fjord

Cordova

Kodiak

Prince William Sound

Seward

Valdez

Whittier

Tatilek

Port

Arrivals

Total WC

Domestic

Total Transp

Other

Figure 9. Percent composition of voyage types for vessels entering Alaskan ports of interest, 2005-

2008. Domestic = voyages within Alaska, Transp = transpacific voyages, WC = voyages from the west 

coast of North America, excluding domestic voyages. 

Voyage histories by port 

On average, vessels that stopped in the PNW were the most frequent contributors to total arrivals at 

every port of interest (Figure 10). Valdez received the large majority of these vessels, followed by 

Whittier, Seward and Kodiak. Vessels that stopped in the San Francisco region were on average the 

next most frequent contributors to total arrivals, and most of these entered Valdez (Figure 10). Vessels 

that stopped in the Southern California region were the third most frequent contributor to total arrivals, 

and also visited Valdez almost exclusively (Figure 10). Vessels that stopped in Asia, Mexico, and 
24

‘other’ areas contributed a small fraction to total arrivals. Vessels from Asia arrived mainly to Valdez, 

Seward, Kodiak and Whittier; vessels from Mexico arrived mainly to Seward and Whittier; and vessels 

from ‘other’ regions arrived mainly to Seward and Whittier (Figure 10). 

0%

20%

40%

60%

80%

100%

Cape Hinchinbrook

College Fjord

Cordova

Kodiak

Prince William Sound

Seward

Tatitlek

Valdez

Whittier

Port

Arrivals

Mexico

Other

South

Pacific

S. CA

SF

NW

Asia

Figure 10. Percent composition of voyage histories for vessels entering Alaskan ports of interest, 2005-

2008. NW = Pacific northwest of United States + British Columbia, SF = San Francisco Bay area, S. 

CA = southern California. 

Voyage histories by vessel type 

Number of arrivals by year 

Tank ships were the largest contributors to total arrivals from 2005 to 2008, followed by passenger 

vessels, freight ships, towing vessels, fishing boats, and ‘other’ types of vessels, respectively 

(Appendix Table 2, Figure 11). There was a decline in 2006 in total arrivals of tank, passenger, freight 

and towing vessels, while arrivals of fishing boats and ‘other’ vessels were similar throughout the study 

period. Tank ship arrivals declined throughout the study period and had the greatest decrease 

(Appendix Table 2, Figure 11). 
25

0

50

100

150

200

250

300

350

400

450

Fishing Freight Passenger Tank Towing Other

Vessel type

Arrivals

2005

2006

2007

2008

Figure 11. The total arrivals of each vessel type per year for vessels entering Alaskan ports of interest, 

2005-2008. 

Number of repeat visits by vessel type. 

Tank ships had the highest rate of repeat visits for 2005 to 2008 (average = 13.46 – 17.6 visits per year 

per vessel, maximum = 24 – 30 visits per year—Table 2). Passenger vessels had the next highest rate of 

repeat visits (average = 6.2 – 7.4 visits per year per vessel, maximum = 10 – 25 visits per year). Towing 

and freight vessels had similar rates of repeat visits (Towing: average = 3.7 – 5.1 visits per year per 

vessel, maximum = 21 – 31 visits per year; freight: average = 3.1 – 5.1 visits per year per vessel, 

maximum = 31 – 34 visits per year; Table 2. 
26

Table 2. Average and maximum number of visits to Alaskan ports of interest 2005-2008 by vessel type. 

Average Fishing Freight Passenger Tank Towing

2005 1.47 5.09 7.41 15.92 5.07

2006 2.00 3.23 6.63 13.46 4.33

2007 1.26 3.56 6.20 16.11 3.71

2008 2.00 3.11 6.23 17.63 4.08

 

 

Maximum Fishing Freight Passenger Tank Towing

2005 8 34 25 30 25

2006 5 31 11 26 21

2007 3 33 10 28 31

2008 6 33 23 24 22

Duration of time in port 

The majority of tank ships left port in less than 24 hours (61%-86%). The number of arrivals staying in 

port 24-48 hours decreased to 10-31% of the arrivals (Table 3). The number of tank ship arrivals 

staying in port continued to decrease as time increased. There was a dramatic drop in total tank ship 

arrivals in 2006, mostly in the 24-48 hours category (Table 3). 

Almost all passenger vessels over the course of the study left port in less than 24 hours (89%-99%) 

(Table 3). 

The majority of freight ships left port in less than 24 hours (69%-84%) (Table 3). The number of freight 

vessels remaining in port was relatively low for the other time categories, but increased slightly in the 

>72 hour category (12%-20%). 

The majority of towing vessels left port in less than 24 hours (74%-90%) (Table 3). 

In 2005 and 2006, the majority of fishing boats left port in less than 24 hours, but the number dropped 

sharply in 2007 and 2008 (76%-30%) (Table 3). The number of fishing boats remaining in port was 

relatively low for the other time categories, except in 2007 and 2008, when a large portion of fishing 

boats stayed in port longer than 72 hours (Table 3). 

Vessels staying in port more than 72 hours were comprised mainly of tank ships in 2005 (Table 3, 
27

Figure 12). In 2006, this category was made up of mostly passenger vessels. In 2007 and 2008, fishing 

vessels had the greatest number of arrivals staying more than 72 hours. Freight ships had the most 

consistent among-year numbers of arrivals staying more than 72 hours. 

Table 3. Duration in port (hours) of arrivals to Alaskan ports of interest 2005-2008 by vessel type. 

2005 Fishing Freight Passenger Other Tank Towing Total Result 

0-24 25 78 177 0 239 53 572 

24-48 2 1 3 0 121 4 131 

48-72 2 3 1 0 19 0 25 

>72 5 11 3 1 14 2 36 

 

2006 Fishing Freight Passenger Other Tank Towing Total Result 

0-24 28 40 116 0 264 39 487 

24-48 3 4 1 1 33 6 48 

48-72 1 1 1 0 7 1 11 

>72 5 6 12 4 3 0 30 

 

2007 Fishing Freight Passenger Other Tank Towing Total Result 

0-24 15 43 116 1 243 37 455 

24-48 3 0 2 1 41 6 53 

48-72 0 4 0 1 11 1 17 

>72 12 9 1 0 5 4 31 

 

2008 Fishing Freight Passenger Other Tank Towing Total Result 

0-24 7 40 136 0 239 34 456 

24-48 5 0 1 1 29 8 44 

48-72 1 2 0 1 3 2 9 

>72 16 12 0 4 6 1 39 
28

0

2

4

6

8

10

12

14

16

18

Fishing Freight Passenger Other Tank Towing

Ship Type

Arrivals

2005

2006

2007

2008

Figure 12. The number of arrivals of each vessel type staying in port more than 72 hours, for vessels 

entering Alaskan ports of interest, 2005-2008. 

Voyage types by vessel type 

Total west coast voyages (combining west coast and west coast-domestic voyages) accounted for the 

majority of tank, passenger, and towing vessel arrivals (Table 4, Figure 13). Domestic voyages 

accounted for the majority of freight and fishing vessel arrivals. Total transpacific voyages accounted 

for the majority of ‘other’ types of vessels, although most of the transpacific voyages occurred in 

passenger, tank and freight vessels. (See Appendix Table 4 for yearly counts). 

Table 4. Average number of each voyage type by vessel type, for arrivals to Alaskan ports of interest 

2005-2008. Transp = transpacific voyages, WC = voyages from the west coast of North America, 

excluding domestic voyages.

 Other Fishing Freight Passenger Tank Ship Towing Total 

Domestic 0 24.75 39.75 16.25 15.25 7.5 103.5 

Other 0.5 0 0.25 1.5 0.25 0.75 3.25 

Total Transp 2.75 0.25 11.5 16.75 14 1.5 46.75 

Total WC 1.25 16.25 11.25 110.5 292 45.25 476.5 
29

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Other Fishing

Boat

Freight

Ship

Passenger Tank Ship Towing

vessel

Grand

Total

Vessel Type

Arrivals

Total West Coast

Domestic

Total Transpacific

Other

Figure 13. Percent composition of voyage types by vessel type, for vessels entering Alaskan ports of 

interest, 2005-2008. 

Voyage history by vessel type 

Vessels that had stopped in the PNW accounted for the greatest portion of arrivals in all vessel types. 

The next highest contributors to total arrivals were vessels that had stopped in the San Francisco Bay 

area, and these vessels were almost exclusively tank ships. Vessels stopping in the Southern California 

region were the third highest contributors to total arrivals, and these also occurred almost exclusively in 

tank ships. Vessels stopping in Asia, Mexico and ‘other’ regions contributed only a small fraction to 

total arrivals. Vessels from Asia were mostly freight, passenger and tank vessels and those from Mexico 

were mostly passenger vessels. Vessels from ‘other’ regions were mostly passenger and freight vessels 

(Table 5, Figure 14). (See Appendix Table 5 for yearly counts). 
30

Table 5. Average numbers of each voyage history type for arrivals to Alaskan ports of interest 2005-

2008 by vessel type. NW = Pacific northwest of United States + British Columbia, SF = San Francisco 

Bay area, S. CA = southern California. 

 Fishing Freight Passenger Tank Towing Other Total 

Asia 0.25 11.5 11.25 9 0.5 1.5 34 

NW 12.5 13.5 125.75 269 47 1.75 469.5 

SF 0.25 0 1.25 163 0.5 0 165 

S. CA 0 0.5 1.5 98.25 0 0.5 100.75 

South Pacific 0.25 1.5 7.25 6.5 1.25 2.25 19 

Other 0.25 2.75 6.75 0.25 2 1.5 13.5 

Mexico 0 0.75 21 0.25 0.75 1.25 24 

0%

20%

40%

60%

80%

100%

Fishing

Freight

Passenger

Tank

Towing

Other

Ship Type

Arrivals

Mexico

Other

South Pacific

S. CA

SF

NW

Asia

Figure 14. Percent composition of voyage histories by vessel type, for vessels entering Alaskan ports of 

interest, 2005-2008. NW = Pacific northwest of United States + British Columbia, SF = San Francisco 

Bay area, S. CA = southern California. 

Conclusions 

The most striking observation of this study is the large drop in all types of vessel arrivals to all ports of 

interest in 2006, except for fishing boats and the port of Prince William Sound (No port given). These 

two categories of arrivals remained at similar levels through the study period. The only total arrival 

category showing increase in arrivals from 2005-2008 was the port of Seward, and the increase was 

small. The ports of Cape Hinchinbrook, College Fjord, Cordova, Kodiak, Valdez and Tatilek all 

experienced decreasing arrivals from 2005-2008, as have the ship categories of freight, passenger, tank 

and towing vessels. The largest decreases were in tank ship arrivals to the port of Valdez. 
31

The largest drop in tank ship arrivals occurred in 2006, which was accompanied by a decrease in tank 

ship repeat visits. It is possible that in 2006 there was the same number of tank ships as in 2005, but 

making fewer visits. In 2007, it appears that the tank ships returned to a normal visitation schedule, 

though arrival numbers continued to shrink. This continued shrinking may be due to a decline in the 

number of different tank ships operating within the area. A similar story may account for the case of 

freight ships as well. 

It should also be noted that the number of fishing vessel arrivals may be artificially low, due to the 

absence of SANS data for vessels weighing less than 300 gross tons. Small vessels may play an 

important role as vectors of hull fouling, but poor documentation makes their relative importance 

difficult to quantify. Some fishing vessel arrival information may be obtained from catch reports and by 

requesting documents from individual harbormasters, but this would be difficult and labor-intensive. 

Similarly undocumented in the SANS data are privately owned recreational vessels weighing less than 

300 gross tons. Floerl (2002) noted the high potential for recreational vehicles to act as fouling vectors, 

since such vessels typically have long harbor residency times, and because there is less financial 

incentive to regularly clean underwater surfaces and maintain the anti-fouling paint. Out of 70 private 

vessels surveyed in the 2002 study, 38% had over 75% of their hulls fouled (Floerl 2002). While it is 

known that many fishing and private vessels travel to Alaska from other US west coast ports, further 

study is needed to assess the potential risks posed by these vessels. 

Risk based on visitation patterns (time in port vs frequency) 

There appears to be an inverse relationship between the amount of time spent in port by a vessel, and 

the frequency of that vessel’s return. This is indicative of two categories of vessels: those that have set 

routes and make numerous brief return trips to the same port, and those that return to port infrequently 

but stay in port for long periods of time. The first type presents a risk of repeat inoculations of NIS 

(potential high propagule frequency), and the second represents risk based on less frequent potential 

inoculations with longer “incubation” time for NIS to release numerous propagules (potential high 

propagule volume). 

Tank ships and passenger vessels represent the high frequency risk category. Tank ships had by far the 

highest average return frequencies, but also had very low times spent in-port (up to 96% of all tank 

ships left port in less than 48 hours and up to 86% left port in under 24 hours). Passenger vessels had 
32

high average return frequencies and low times spent in port (up to 99% of all passenger vessels leave 

port in less than 24 hours). Thus, these two vessel types represent relatively high risk based on potential 

frequency of inoculation and relatively low risk based on potential per-vessel volume of inoculation. 

Another risk factor for these two vessel types is that they are most often from west coast/west coastdomestic voyages. These types of voyages are shorter than transpacific voyages, with shorter exposure 

to oligotrophic, open ocean water that may be detrimental to coastal fouling organisms. Most tank ship 

arrivals have originated or stopped in Southern California, the San Francisco Bay area, or Puget 

Sound—which are among the most heavily NIS-invaded regions on the west coast of the United States 

(Cohen and Carlton 1995, Wonham and Carlton 2005, Cohen et al. 2005). Many passenger vessels 

arriving in Alaska had stops in Mexico and Asia, as well as the South Pacific and ‘other’ regions—

Asia, in particular has been the source of most of the aquatic invasive species in the northeast Pacific 

(Wonham and Carlton 2005). While passenger vessels and tank ships generally maintain their hulls in 

such a fashion as to minimize fouling, the sheer numbers of these vessels repeatedly arriving to the 

Prince William Sound region greatly increases the possibility of accidental introduction. 

Freight and fishing vessels represent the high propagule volume risk category, in having relatively 

irregular but long visits to Alaskan ports. Fishing boats had the lowest average return frequency, and 

over the course of the study their time spent in port changed dramatically. In 2005 and 2006 the 

majority (76% in 2006) of fishing boat arrivals stayed in port for less than 24 hours, but by 2007 this 

had dropped to only 50%. 2008 saw the majority of fishing boat arrivals staying in port for longer than 

72 hours (74% in 2008). Freight ships also had a low average return frequency (though the average is 

skewed upward by one ship, which returned to Kodiak over 30 times per year). While total freight 

vessel arrivals decreased over time, the number of vessels staying over 72 hours did not change. For 

vessels that stayed in port longer than 72 hours, freight ships had the consistently highest numbers, and 

fishing boats had the most rapidly growing numbers. Arrivals from these types of vessels were most 

often from domestic voyages, and represent a relatively low risk of introducing new NIS. However, in 

the future they may act as vectors for secondary introductions by transporting previously introduced 

species from one Alaskan port to another. Also, many freight ships previously stopped in Asian ports 

before coming to Alaska and could represent a source of NIS from that region. 

Towing vessels generally did not fall into either risk category. On one hand, towing vessels did not 

have a high average return frequency, though the average was skewed upward by one vessel that visited 

over 20 times per year. On the other hand, up to 97% of all towing vessels leave port in under 48 hours 
33

(up to 90% in under 24 hours). Towing vessel arrivals are most often from west coast/west coastdomestic voyages, which as previously stated, may experience higher organism survival rates. Also 

many towing vessels stopped in the Southern California and San Francisco regions that have extensive 

invasive fouling communities. Another factor that should be considered is that towing vessels usually 

travel at slower speeds than other vessel types, which may reduce the mortality of fouling organisms 

while underway. They may also haul barges that contain a high density of fouling organisms, though 

there is no data available as to what percentage of towing vessels are hauling barges. 

Risk based on port 

The threat of invasion is not uniform for all ports due to the varying composition of arrivals to each 

port of interest, and the different risks posed by each vessel type as discussed above. Of the nine ports 

of interest, Valdez, Whittier, Seward and Kodiak have the highest potential risk for NIS being 

introduced from hull fouling. 

The risk posed to Valdez comes from the large volume of traffic from San Francisco Bay, Southern 

California, and the Puget Sound. Valdez traffic is composed almost exclusively of tank ships, which 

have an accumulated risk associated with them from repeat inoculations. While tank ship operators 

maintain clean hulls to reduce drag and cut fuel costs, 'functionally clean' may not translate into 

ecologically clean. Small communities of fouling organisms may persist in sea-chests, around 

propellers and other complex areas of the hull. Furthermore, the repeat inoculations may occur across 

an array of weather conditions and seasons, thus increasing the likelihood of an introduction in ‘ideal’ 

conditions. 

Whittier is at risk from the high volume of passenger vessel and towing vessel traffic from the PNW. 

Vessels arriving from the PNW may experience higher fouling survival rates due to shorter voyage 

durations, and fewer changes in the physical environment. Towing vessels may also have higher 

survival rates from because of slow average voyage speeds and from hauling possibly contaminated 

barges. A relatively large proportion of passenger vessel arrivals have also stopped in Mexico and a 

variety of transpacific locations that may be sources of NIS; they occur in the summer months when 

propagule pressure is generally highest; and the high return rate of the vessels allows for potential 

repeat inoculations across a variety of conditions. 
34

Seward, like Whittier, is at risk from passenger vessels arriving from west coast and transpacific 

voyages. The majority of passenger vessels arriving to Seward come via the PNW and a large 

proportion of these vessels have also stopped in Asia and/or Mexico. Passenger vessels from these 

regions, as discussed above are a risk for primary introductions from repeat inoculations. 

Domestic freight ships and fishing boats may present a risk to the port of Kodiak from secondary 

invasion by already introduced NIS arriving from other Alaskan ports. Wasson et al (2001) found that 

regional traffic was a significant vector for secondary invasions to non-commercial harbors. It was 

concluded that resident fishing boats and pleasure crafts act as ‘stepping stones’ for exotic species to 

spread out of San Francisco Bay into nearby regions. In Kodiak, the long “residence time” of fishing 

boats and freight ships may allow for the accumulation of extensive fouling communities, or allow preexisting fouling to release large numbers of propagules into the surrounding port waters. Additionally, 

freight ship arrivals from transpacific and west coast voyages to Kodiak may also present some risk of 

primary NIS introductions. 
35

Hull Maintenance 

Hull Maintenance Overview 

Currently, there is little regulation regarding hull husbandry practices. Section 2.2.23 of the EPA’s 

Vessel General Permit includes the most specific requirements: 

“Vessel owner/operators must minimize the transport of attached living organisms 

when they travel into U.S. waters from outside the U.S. economic zone or when 

traveling between COTP zones. 

Whenever possible, rigorous hull-cleaning activities should take place in drydock, or 

another land-based facility where the removal of fouling organisms or spent 

antifouling coatings paint can be contained. If water-pressure based systems are used 

to clean the hull and remove old paint, use facilities which treat the wash water prior 

to discharge to remove the antifouling compound(s) and fouling growth from the wash 

water. 

Vessel owner/operators who remove fouling organisms from hulls while the vessel is 

waterborne must employ methods that minimize the discharge of fouling organisms 

and antifouling hull coatings...” 

Any non-compliance with the requirements of the VGP constitutes a violation of the Clean Water Act. 

For discharges incidental to normal operations (i.e. discharges that are not ballast), the Vessel General 

Permit (VGP) applies to non-recreational vessels 79 feet or longer, with the exemption of commercial 

fishing vessels. The exemption of fishing vessels in ship husbandry requirements may pose a 

significant risk to the ports of Alaska, where commercial fishing is prevalent and economically 

important. Numerous domestic and west coast fishing vessels arrive to and from Alaskan ports each 

year, though due to poor documentation it is difficult to quantify the potential risk. 

 The issue of hull fouling is also addressed briefly in Title 33 of the Code of Federal Regulations, Part 

151, which concerns vessels carrying oil, noxious liquid substances, garbage, municipal or commercial 

waste, and ballast water. Two lines that are in sub-section 2035, concerning required ballast water 

management practices, cover a commercial ship’s responsibility regarding hull fouling: 
36

(5) Rinse anchors and anchor chains when you retrieve the anchor to remove 

organisms and sediments at their place of origin. 

(6) Remove fouling organisms from hull, piping, and tanks on a regular basis and 

dispose of any removed substances in accordance with local, State and Federal 

regulations. 

According to 33 CFR 151.2007, any violation of this sub-part is subject to a civil penalty of up to 

$27,500 per day of continuing violation, and any person who knowingly violates this sub-part is guilty 

of a class C felony (Showalter and Savarese 2004). However, the regulations go on in 33 CFR 151.2010 

to exempt certain vessels from the required ballast water practices: 

Two types of vessels are exempt from the requirements in §§151.2035, 151.2040, 

and 151.2045: 

(1) A crude oil tanker engaged in the coastwise trade. 

(2) A Department of Defense or Coast Guard vessel subject to the requirements 

of section 1103 of the Act, or any vessel of the Armed Forces, as defined in the 

Federal Water Pollution Control Act (33 U.S.C. 1322(a)) that is subject to the 

“Uniform National Discharge Standards for Vessels of the Armed Forces” (33 

U.S.C. 1322(n)). 

This exemption covers the majority of tank ships that travel to and from Alaska. However, tank ship 

companies conduct voluntary hull maintenance operations, generally in conjunction with regular dry 

dock inspections mandated by Merchant Class Societies such as the International Association of 

Classification Societies, Ltd (IACS), and the US Coast Guard. These two entities typically require at 

least one dry dock inspection of a ship's hull every five years (Takata et al 2006). Depending on the 

classification and age of the ship, dry dock inspections sometimes occur twice every five years (IACS 

REC 076, 088, 096). While these inspections are largely only for structural and safety purposes, vessel 

operators generally use the opportunity to clean the hull and re-apply anti-fouling paint as needed. 

Because extensive fouling may reduce the fuel efficiency of a vessel, operators may also sometimes opt 

to conduct interim in-water cleanings between required five year dry dock inspections (Takata et al 

2006). It should be noted that the vessel operators clean hulls based on functional necessity rather than 
37

environmental reasons; as such, a level of fouling that does not interfere with ship operations may be 

allowed to persist. Tank ships that operate in Prince William Sound are generally cleaned by high water 

pressure washing on dry dock at least once every five years (Takata et al 2006, Personal 

Communication). 

Hull Maintenance Procedure 

Hull maintenance operations in a dry dock facility are usually conducted in a similar manner. For large 

vessels such as tank ships, the ship is maneuvered through gates into an enclosed dock. The dock gates 

are then shut, and the water slowly drained. In smaller vessels, the ship may be physically lifted from 

the water to the work area. In either case, blocks are placed on either side of the hull to support the 

vessel while it is out of the water. The vessel is then blasted with a high pressure wash (3000-8000 psi) 

to remove fouling organisms, before being assessed for damage and paint wear. Often, the operators 

 opt for a full or partial reapplication of the anti-fouling paint. It is important to note that the areas that 

are covered by the hull supports cannot be painted, creating the possibility that certain areas of the hull 

go up to ten years without a fresh application of paint, which may decrease the anti-fouling properties 

of those areas (Davidson et al 2006c, Takata et al 2006). 

In-water cleanings are performed by divers either manually scraping and suctioning fouling off the 

hull, or by using mechanical brush systems such as the Submerged Cleaning and Maintenance Platform 

(SCAMP). While the SCAMP and other systems provide prevention against detritus falling to the seafloor, the effectiveness of containment is variable. In addition, many in-water cleanings on smaller 

vessels provide no containment at all, allowing fouling organisms to escape to the surrounding water or 

sink to the bottom. Floerl et al (2005) found that while in-water cleanings may minimize fouling in the 

short term, it poses a large biosecurity risk, and may actually encourage the spread of fouling 

organisms if the effluent is not properly contained. 

Anti-Fouling Systems 

Until recently, and for the last 30 years, the most commonly applied anti-fouling paints contained 

tributyl tin (TBT), a highly effective biocidal agent. However, findings that linked TBT leaching from 

ship hulls to a number of negative ecological consequences led to a ban of TBT use in the United States 

in 1988, followed by a global phase-out and world wide ban in January 2008 by the International 

Maritime Organization (Takata et al 2006, Davidson et al 2006c, Showalter & Savarese 2004, Savarese 
38

2005). Other kinds of anti-fouling paints have since been introduced as replacements, though they are 

generally considered less effective. The paints are divided into two main categories: TBT-free biocidal 

paints that utilize zinc or copper, and silicon based non-biocidal paints that are extremely smooth. In 

the first category, the paints simply replace TBT with copper or zinc as the active ingredient. In the 

latter category, the slippery silicon based paints make it difficult for organisms to adhere to the surface, 

especially while underway (Takata et al 2006). 

Vessels also often have specialized Marine Growth Protection Systems (MGPS) installed in their seachests. The primary purpose of a MGPS is to eliminate biofouling in seawater circulation systems. 

Through the use of strategically placed anodes and cathodes, in-coming seawater is electrolyzed with 

either copper or hypochlorite ions, depending on the manufacturer (ClearFlo System Operation, Wilson 

Walton; Sanilec, Severn Trent De Nora). The resulting solutions provide an inhospitable environment 

for fouling organisms. MGPS may be essential treatments for NIS, because sea chests can host 

aggregations of fouling organisms: within a single sea-chest Coutts et al (2003) found not only typical 

fouling organisms, but also such surprising finds as the introduced European clam (Corbula gibba), 

and three introduced Green crabs (Carcinus maenas), two of which were ovigerous females capable of 

releasing viable propagules. The same paper also mentions that the unique habitat provided by a seachest has yielded an invasive sea-star, Asterias amurensis, and several species of small fish. In a later 

paper, Coutts & Dodgshun (2007) found that while MGPS systems significantly reduce fouling by 

sessile and sedentary organisms, the systems have little influence on the occurrence of mobile species 

within sea-chests; therefore, MGPS may reduce, but not eliminate entirely, the risk of sea-chests as 

vectors for introductions. 

Hot Spots 

Because a vessel's hull is not uniform, hull fouling does not occur evenly. Areas that have either higher 

complexity like heterogeneous surfaces or areas of uneven paint, or areas of low water velocity create 

conditions that encourage fouling organisms. These areas include sheltered areas around the propellers, 

bilge keels, rudders, bow thrusters, intake pumps, and sea chests, and also the dry docking support 

strips and waterlines where anti-fouling paint is applied irregularly (Coutts et al 2003; Coutts & Taylor 

2004; Davidson et al 2006c). In vessels that travel at high speeds (above 15 kt) very little fouling is 

observed on the laminar parts of the hull, but fouling may still persist in the areas mentioned above 

where organisms can be shielded from strong shearing forces. In vessels that travel slower than 10 kt, 
39

there is a greater incidence of fouling organisms surviving on all parts of the hull (Takata et al 2006, 

Davidson et al 2006). 

Other Risk Factors 

Besides hull complexity, vessel speed, and the condition of anti-fouling paint, other factors contribute 

to the level of fouling found on a ship’s hull. Vessels that experience rapid and drastic changes in 

salinity and temperature, such as those that pass through both marine and fresh water or conduct transequatorial voyages may experience reduced survivorship of fouling organisms by subjecting them to a 

range of conditions outside their physiological limits (Davidson et al 2006c, Takata et al 2006). On the 

other hand, Coutts & Taylor (2004) found that vessels that travel through similar latitudes may 

experience increased survivorship of fouling organisms by retaining relatively consistent temperature 

and salinity levels. Shorter voyages may also be beneficial to coastal fouling organisms, because they 

would be exposed for a shorter time to oceanic conditions before arriving at port. A combination of 

these two factors may mean that there is a higher risk of secondary contamination of Alaskan waters 

from vessels traveling on coast-wise voyages (e.g., from Puget Sound or San Francisco Bay) than of 

primary contamination from vessels traveling from more exotic locations. Traveling to a wide range of 

locations may also be a risk factor because it increases the odds that an organism with a broad range of 

tolerances will attach to the hull. 

Furthermore, in addition to voyage routes, invasion risk may be influenced by the organisms 

encountered in each port. A number of fouling organisms have been introduced far outside their places 

of origin, and are becoming pandemic. In these cases, the rate of new introductions is accelerating, in 

part due to increasing sources for secondary introductions, and the spread of physiologically tolerant 

NIS (Cohen & Carlton 1998). Secondary introduction poses a risk to Alaska from domestic and coastwise ports where introduced species have already demonstrated an ability to successfully invade. For 

an index of invasive species and the regions they have been recorded in, see Appendix Table 6. 

The level of fouling accumulated is related to the amount of time a vessel has spent in port. Because 

larval settlement may be prevented by speeds as slow as 2 KTS (Davidson et al 2006c), accumulation 

occurs while a vessel is docked, and increases over time. This is especially true in protected ports with 

restricted flow and poor flushing where propagules may be retained in the water column for long 

periods of time (Takata et al 2006). Due to reproductive periodicity of fouling organisms, propagule 

amounts can vary by season, with summer and spring typically having higher propagule numbers than 
40

winter and fall (Davidson et al 2006c). 

Perhaps the most important factor contributing to fouling on hulls in the amount of time passed since 

the last hull cleaning. Coutts and Taylor (2004) hypothesized that the relatively high levels of fouling 

they observed in archived maintenance videos was because the vessels sampled were all near the end of 

their maintenance cycles. Ruiz et al. (2000) sampled the fouling communities of two tank ships: one 

had not been cleaned in dry dock for approximately 2 years; one had been cleaned in dry dock within 

about 6 months. The two ships exhibited extremes in the quantity and diversity of organisms: the ship 

that had not been cleaned in approximately 2 years had an extensive fouling community, with abundant 

mussels and associated worms, crustaceans, and sediments (including one NIS), while the ship that had 

been cleaned recently had few mainly present in the sea chest. 

Example Hull Maintenance Schedules 

Detailed maintenance information was obtained for 18 of the 26 tank ships known to operate within 

Prince William Sound from 2005 to 2008. This information was acquired through the California 

Marine Invasives Program at the California State Lands Commission. Since January 2008, the CSLC 

has maintained an extensive database of the maintenance histories of vessels arriving to California. The 

data presented here represents a small subset of total vessels within that database, including those tank 

ships within our study that have been to California since the Marine Invasives Program began (Table 

6). 

The CSLC obtains the information from the maritime industry by providing comprehensive reporting 

forms. The vessel operators must complete and submit the form within 60 days of receiving a request 

from the commission. Among the information included in the data: 

1. Dates and location of last out of water maintenance. 

2. Date of last full or partial coat of anti-fouling paint application, type of biocide used, and 

locations of the hull where applied. 

3. Whether Marine Growth Protection Systems have been installed in the sea-chests. 

4. Dates of in water cleaning, if applicable. 

5. Whether the vessel has, since the last cleaning: recently visited freshwater or tropical areas, 

been through the Panama Canal, or stayed ten consecutive days in a single port. 
41

Furthermore, several shipping companies known to operate within Prince William Sound were 

contacted directly and interviewed regarding their maintenance policies. Alaska Tanker Company, 

SeaRiver Maritime Inc, Polar Tankers and Seabulk Tankers Inc are responsible for the majority of tank 

ship traffic arriving to Prince William Sound. Of these four, only SeaRiver Maritime Inc could not be 

successfully reached; however, sufficient data regarding SeaRiver Maritime’s maintenance practices 

was obtained from the CSLC database. 

All of the shipping companies interviewed reported conducting hull cleanings with a high pressure 

wash on dry dock at least once every five years. Of the 18 vessels, the greatest duration of time since 

last maintenance or build was five years, and the average time since last maintenance or build was two 

years (Table 6). As noted in the sections above, two years is enough time for extensive fouling to 

accumulate (Ruiz et al 2000). Only two vessels underwent in-water cleanings since the last reported 

drydock. The majority of the vessels had Marine Growth Protection Systems installed in sea-chests, 

and also had a full coat of anti-fouling paint reapplied at the last drydocked maintenance (Table 6). 

However, many of the vessels did not paint non-hull surfaces such as thrusters and rope guards, or the 

previous dry dock support strips (For specific areas of the hull painted and the type of paint used, see 

Appendix Table 7). As discussed earlier, these areas may act as refuges for small groups of fouling 

organisms. Furthermore, many vessels spent over 10 consecutive days in a single port, thereby 

increasing the risk of fouling accumulation. The ports where the 10+ day stays occurred are places 

where NIS are known to be established. The majority of vessels rarely visited tropical ports or the 

Panama Canal, and are therefore less likely to transport invasive species from these areas. Only three 

vessels have regularly visited freshwater ports, and are likely to have significantly less fouling due to 

the rapid salinity changes (Table 6). As a whole, the 18 vessels may present risk associated with 

secondary introductions, by carrying fouling organisms on irregularly painted surfaces. 
Table 6. Hull maintenance of tank ships operating in Alaskan ports of interest 

ReportYear Vessel Name

Vessel 

Delivery Date

Out Of 

Water 

Maintenance 

Date

Out Of 

Water 

Maintenance 

Country

In Water 

Cleaning 

Date

Years since 

maintenance 

or delivery Coating Level

Last Full 

Coat Date

Sea 

Chests 

MGPS 

Installed

?

Days in 

FW Port 

Visit 

since last 

cleaning

Days in Tropical 

Port Visit 

since last 

cleaning

Days in 

Panama 

Canal 

Visit 

since last 

cleaning?

2008 ALASKAN EXPLORER 21-Mar-05 3 Full Coat Applied Y 2009 ALASKAN EXPLORER 21-Mar-05 4 Full Coat Applied Y 2008 ALASKAN FRONTIER 11-Aug-04 4 Full Coat Applied Y 1 2009 ALASKAN FRONTIER 11-Aug-04 5 Full Coat Applied Y 1 

2008 ALASKAN LEGEND 18-Aug-06 2 Full Coat Applied Y 1 2009 ALASKAN LEGEND 18-Aug-06 3 Full Coat Applied Y 1 2008 ALASKAN NAVIGATOR 23-Nov-05 3 Full Coat Applied Y 1 

2009 ALASKAN NAVIGATOR 23-Nov-05 4 Full Coat Applied Y 1 

2009 CAPTAIN H. A. DOWNING 23-Sep-06 Canada 3 Full Coat Applied N 26 20 2008 KODIAK 16-Nov-05 Singapore 3 Full Coat Applied Y 2009 KODIAK 16-Apr-08 USA 0 Full Coat Applied Y 2008 MISSISSIPPI VOYAGER 01-Mar-07 USA 1 Full Coat Applied 3 3 

2009 MISSISSIPPI VOYAGER 12-Sep-09 USA 0 Full Coat Applied 1 

2009 OVERSEAS NEW YORK 11-Apr-08 1 Full Coat Applied Y 26 1 1 2008 POLAR ADVENTURE 01-Sep-04 4 Full Coat Applied N

2008 POLAR DISCOVERY 01-Jun-06 Singapore NA 2 Full Coat Applied N2009 POLAR DISCOVERY 01-Jun-06 Singapore 10-Oct-06 3 Full Coat Applied Y 9 1 

2008 POLAR ENDEAVOUR 01-Jun-04 Singapore 4 Full Coat Applied N

2009 POLAR ENDEAVOUR 21-Aug-09 Singapore 7-Dec-08 0 Partial Coat 21-May-09 Y 

2008 POLAR ENTERPRISE 01-Jan-06 2 Full Coat Applied N

2009 POLAR ENTERPRISE 23-Oct-06 Spain 3 Full Coat Applied Y 1 1 

2008 POLAR RESOLUTION 1-Aug-05 Singapore 3 Full Coat Applied Y 

2009 POLAR RESOLUTION 3-Aug-05 Singapore 4 Full Coat Applied N 

2008 S/R BAYTOWN 07-Sep-06 Singapore 2 Full Coat Applied Y 1 1 1 

2009 S/R BAYTOWN 25-Aug-06 Singapore 3 Full Coat Applied Y 39 2 

2008 S/R LONG BEACH 15-May-07 Singapore 1 Full Coat Applied Y 2 

2009 S/R LONG BEACH 15-May-07 Singapore 1 Full Coat Applied Y 1 

2008 SEABULK ARCTIC 29-Aug-06 Panama 2 Full Coat Applied 4 1 

2009 SEABULK ARCTIC 07-Jul-08 Singapore 1 Full Coat Applied N 1 

2008 SEABULK PRIDE 27-Feb-06 USA 2 Full Coat Applied N 2 1 

2009 SEABULK PRIDE 12-Sep-08 Singapore 1 Full Coat Applied N 1 

2008 SIERRA 24-Jul-06 Singapore 2 Full Coat Applied Y 2009 SIERRA 18-Dec-08 Singapore 0 Full Coat Applied Y 1 
43

Hull fouling sampling methods and recommendations 

Introduction 

Studies of biofouling on ship’s hulls have employed various sampling and analysis techniques 

(summarized in Table 7). However, aside from Davidson et al. (2006b), there are few studies that 

evaluate and compare the efficiency and effectiveness of several techniques. Four techniques have been 

commonly used to sample hulls: (1) using divers to collect specimens and conduct underwater photo 

quadrats; (2) collecting specimens and photo quadrats immediately after a vessel has been drydocked; 

(3) using archival video footage of under water in lieu of Drydock (UWILD) inspections; and (4) using 

remotely operated vehicles (ROVs) to conduct video transects. By utilizing existing literature and prior 

experiences, Davidson et al (2006b) qualitatively assessed these four techniques for strengths and 

weaknesses across ten criteria. These criteria included: representativeness of vessel population; 

representativeness of vessel arrivals to a specific port; possible constraints on measuring biofouling 

extent; possible constraints on measuring species composition; possible constraints on measuring 

viability; possible constraints on accessing sea-chests; availability of vessel history; access to vessels; 

sampling duration; and cost. Of the ten criteria Davidson et al. (2006b) used, we will summarize those 

likely to be most relevant to this study: (1) cost; (2) representativeness of sampling; and (3) type and 

quality of data obtained. 

Methods 

Visual Rank Assessment 

A rank scale of fouling intensity has been developed and used along with hull maintenance 

questionnaires to evaluate fouling on smaller vessels such as pleasure yachts (Floerl et al. 2002, 2005, 

Ashton et al. 2006). The scale is based on approximate percentage cover on hull surfaces visible from 

the surface and number of different identifiable taxa of marine invertebrates and plants comprising 

fouling assemblages and ranges from 0 (no fouling) to 5 (very heavy fouling). This type of assessment 

may be useful in broadly evaluating fouling and risk patterns associated with smaller vessels (e.g., 

recreational and fishing boats) entering Alaska. 

Diving 

Divers have been used in a number of studies to conduct surveys (Cohen et al. 1998, 2001, 2002, 

2005a, 2005b; Godwin 2003; Mineur et al. 2007; Ruiz and Smith 2005; Davidson et al 2006c). Many 
44

of these studies have been cursory, noting only presence-absence (e.g., Cohen et al. references cited 

above) or focused on individual taxa or groups (e.g., Mineur et al., surveying algae on hulls). Ruiz and 

Smith (2005) surveyed nine vessels over a two week period, in April 2004 in the Port of Oakland, 

California. Divers collected biota and video data from transects along selected parts of the hull, and 

obtained species presence/absence data, live/dead data and surface area data. While they found a 

notable paucity of organisms on all of the hulls inspected, only one vessel was without any visual 

fouling. The extent of fouling varied greatly from one vessel to the next, leading the authors to 

conclude that further studies with larger sample sizes are needed; however they also observed that nonhull underwater locations were the most important sites for biota abundance and diversity. 

Dry Dock 

Surveys conducted on drydock have also been conducted in a number of studies (Gollasch 2002; 

Minchin and Gollasch 2003; Davidson et al 2006a; Drake and Lodge 2007; Coutts et al. 2003). In the 

most comprehensive of these studies, Gollasch et al. (2002) sampled vessels visiting German ports for 

3 years, from 1992 to 1995. Over the course of the study, a variety of locations on 186 ships were 

sampled, including 131 hull samples obtained by using scrapers immediately after a vessel was drydocked. Samples were identified and assigned to four different categories: native, established nonnative, non-established non-native, and cryptogenic. They found that 74% of all species found in hull 

samples were non-native to the North Sea. Furthermore, 96% of all samples taken included at least one 

NIS. While they found that the majority of the non-native species found were from warmer climates 

and therefore unlikely to become established, 22% of total non-native species found were considered to 

pose a risk of successful introduction. 

Archival Video Footage 

Several studies have used archival hull inspection video footage to extract fouling data (Coutts and 

Taylor 2004; Davidson et al. 2006c). Coutts and Taylor (2004) obtained underwater video for 30 

randomly selected vessels from commercial diving libraries. Eight locations on the vessels were chosen 

to investigate: the hull, propeller, bulbous bow, bilge keel, rudder, rope guard, sea-chest grating, and 

support block strips. In each of the eight locations, the video was randomly paused 5 times on as many 

vessels as possible. Biofouling organisms were identified to broad taxa (i.e. green algae, brown algae) 

and assigned to four categories representing the spectrum of fouling progression: A= no fouling, B= 

fine algae/slime C= encrusting organisms, D= macrofauna. The study found that while 54% of the 
45

quadrat areas surveyed had no visible fouling, category B organisms were found in high concentrations 

on propellers, bulbous bows, bilge keels, rudders and rope guards. The study concluded that using 

video footage may be a cost effective method of assessing risk, though issues with clarity prevented 

finer taxonomic resolution. 

ROV 

The use of ROVs to conduct hull fouling surveys is a relatively new technique. While it has been used 

in a number of benthic habitat surveys (Pacunski et al. 2008; Parry et al. 2003; Parry et al. 2002), hull 

fouling studies using ROVs are relatively rare (Davidson et al 2009). However, the commercial use of 

ROVs to inspect the hulls of ships for structural damage is more common in the shipping industry 

(Lynn and Bolander 1999; Harris and Slate 1999), and ROV services are often offered by the 

commercial dive companies that perform inspections. In one of the few hull fouling studies to make use 

of ROVs, Davidson et al (2009) conducted ROV video surveys on 13 containerships docked at the Port 

of Oakland in May 2006. Using a three person team to monitor and control the ROV, the researchers 

examined the hulls, rudders, propellers and stern tubes of all vessels surveyed over a series of transects. 

Wherever possible, the team also inspected bulbous bows, bow thruster gratings and intake gratings. 

Video was used for coarse taxonomic identification; divers were deployed on a subset of vessels to 

obtain biological samples for finer resolution. The researchers found low levels of observable fouling 

on the majority of the vessels surveyed, and also found that rudders, bow thrusters and stern tubes were 

fouled more frequently than other submerged areas. While noting that many factors play a role in 

fouling accumulation, the researchers found a significant positive relationship between taxa richness 

and time out of dry dock. 
Table 7. Hull fouling studies and methods Authors 

Number of ships sampled Location 

Types of ships 

Technique used Data Collected 

Ashton G, Boos K, Shucksmith R, Cook E (2006) 866 Scotland Private Yacht 

Visual rank assessment Percent cover, vesse

Coutts ADM, Moore KM, Hewitt CL (2003) 1 

Sydney, Australia Passenger 

Dry dock collection presence/absence 

Coutts ADM, Taylor MD (2004) 30 New Zealand 

Merchant vessels 

Archival video footage Taxa richness, perce

Coutts ADM, Dodgshun TJ (2007) 42 New Zealand 

Miscellaneous commercial vessels 

Dry dock collection 

Presence/absence, vhistory, organism morichness 

Davidson I, Sytsma M, Ruiz G (2006a) 17 

Columbia River, OR 

Miscellaneous commercial vessels 

Dry dock sampling, archival video 

 Taxa richness, taxa percent cover, vesse

Davidson I, Ruiz G, Sytsma M, Fofonoff (2006c) 2 

Suisun Bay, CA 

Obsolete National Reserve Defense Fleet vessels 

Diver photo quadrats, specimen collections 

Species richness, pecover, species abund

Davidson I, Brown C, Sytsma M, Ruiz G (2009) 22 

Port of Oakland, CA container ships 

Diver and ROV video surveys, limited specimen collections 

Presence/absence acover at broad taxonlevels, species richnehistory 

Drake JM, Lodge DM (2007) 1 Lake Ontario Bulk carrier 

Dry dock collection 

Species richness, taxabundance 

Farrapeira CM, de Melo AV, Barbosa DF, Silva HM (2007) 32 Recife, Brazil 

Miscellaneous commercial vessels 

Diver specimen collections 

Presence/absence, srichness 

Floerl O, Inglis GJ, Hayden BJ (2002) 783 New Zealand Private yacht 

Visual rank assessment, video transects Percent cover, vesse

Godwin LS (2003) 8 Oahu, HI Barges 

Diver specimen collections Presence/absence 

Gollasch S (2002) 186 

German ports along North Sea 

Container ships, and miscellaneous commercial vessels 

Dry dock collection Species richness 

Mineur F, Johnson MP, Maggs CA, Stegenga H (2007) 22 Sete, France 

Unspecified commercial vessels 

Algae collections while snorkelingl 

Presence/absence, vhistory 

Ruiz GM, Smith G (2005) 9 

Port of Oakland, CA container ships 

Diver video surveys and specimen collections 

Presence/absence, pcover, taxa richness, distribution of organis
47

Pros and Cons 

Cost 

Using archival video footage from UWILD inspections is the least expensive option, because the video 

has already been taken and the footage must simply be requested from the video inspection company 

after obtaining permission from vessel owner/operators. (Davidson et al 2006b). Collecting data during 

a scheduled dry-docking event is also a relatively inexpensive option. However, because tank ships in 

the northeast Pacific usually drydock in Asia, costs would include travel to Asian drydock facilities that 

service the tank ships. Smaller vessels such as fishing boats and barges could be sampled at regional 

drydock facilities. Visual rank assessment is also relatively inexpensive, and can be conducted by 

volunteers, resulting in a large amount of data (e.g., 866 vessels sampled by Ashton et al. 2006). The 

use of divers and ROVs are the most expensive options, but costs may be lowered if divers are 

available within the institution conducting the sampling: otherwise, commercial divers would have to 

be contracted. ROV costs may also be mitigated by using an institution that has one or more ROVs 

available or partnering with such an institution (e.g., the Washington Department of Fish and Wildlife 

has an ROV). If a relatively long-term project is anticipated, purchase of an ROV may also be costeffective. Both drydock and diver surveys could yield biological samples that would require fixation, 

transport, and identification by taxonomic experts that would add additional costs. 

Representativeness 

To prevent bias from being introduced into the study, samples should be representative of the vessel 

population being sampled. Dry-docking events and archived video inspections occur at regular 

intervals when fouling is most likely, i.e., every five years for dry-docking, and once between dry 

docks for underwater video inspections (Davidson et al 2006b). Sampling of vessels at the end of their 

maintenance routines may bias studies toward the most fouled conditions, and should accordingly be 

identified as such. On the other hand, diver and ROV surveys can be conducted at any point in a 

vessel's maintenance schedule, and provide a more representative sampling regime. Visual rank 

assessment is the least representative method, as it can only be conducted reliably on small vessels, and 

is limited to parts of the hull that can be seen from the surface. 

Data Type and Quality 

The type and quality of data obtained are the most important criteria when considering the overall goals 
48

of the study. ROVs, archival video footage, and visual rank assessment can provide a large quantity of 

data, but, because of limitations in resolution, there is a limited ability to interpret the information. In 

this case, fouling organisms must be grouped into broad categories, accompanied by abundance counts 

or percent cover for each category. ROV and archival video footage may be adequate at providing a 

gross measure of how much fouling is present, but cannot identify all of the species present or quantify 

the abundance of each species. Archival footage and visual rank assessments may be less effective than 

ROV video because there is no control over what areas of the hull are recorded in the archived footage, 

while ROV video can be taken on predetermined transects and/or “hot spots” of interest. Thus, it would 

be difficult to devise a uniform study design using archival video. Diver and drydock surveys, on the 

other hand, provide lower quantities of higher quality data. These two methods allow for sample 

collection and identification of biota to low taxonomic levels. This information may be accompanied 

by other quantitative information about representative sections of a given vessel hull (e.g., visual 

assessments to accompany biota samples), though gathering of such data may be limited to the 

accessible parts of the hull. In the case of drydock surveys, only certain portions of a vessel’s hull will 

be accessible for collecting biological samples. For example, if specimens could only be collected 

from areas accessible by ladder, the majority of the hull would not be characterized. Also, during the 

dry-docking procedure, some mobile organisms associated with the fouling assemblage (e.g., copepods, 

amphipods, shrimp) may leave the hull, and other organisms may die and begin to decompose before 

sampling is conducted. 

If a general measure of total amount of hull fouling in broad taxonomic categories is the goal, then 

drydock surveys and archival video footage may be possible options for hull fouling surveys. However, 

drydock surveys may be impractical for vessels entering Alaska ports, because dry-docking of the 

major vessel type, tankers, is done at foreign facilities. Archival footage is problematical because of 

the potential lack of resolution and control over sample design, but may be useful in refining a subset 

of vessels to focus higher resolution studies on (see recommendations section). Likewise, visual rank 

assessment is useful only for identifying broad taxonomic categories on small vessels. These methods 

may introduce unacceptable bias to a hull fouling study if the study goal is to assess representative 

cross sections of individual hulls and/or a vessel population. The two other options, ROV and diver 

surveys, are examined in more detail. 
49

Assessment of ROV and Diver Sampling 

ROV 

ROVs can provide data that is more extensive than that which can be taken within the depth, spatial, 

and time limits of diver collections. While diver time underwater is limited by physiological and air 

supply constraints, ROVs have no such limits and may survey the entire hull of a vessel with relative 

ease. Without people in the water, safety restrictions are also less stringent, and it may be easier to 

receive port and vessel permissions to conduct surveys (Davidson et al. 2006b). Effective ROV surveys 

also require fewer support personnel than diving surveys. Operation of the ROV requires at least 3 

people: a pilot, someone to manage the umbilical lines, and someone to monitor the video. A diving 

survey requires at least two divers, a land coordinator for safety, and if samples are collected, a team of 

biologists to immediately sort and preserve specimens. For visual surveys, ROV data appears to be 

comparable to diver observations. For example, in a study of the abundances and distribution of 

burrowing megafauna, Parry et al. (2002) found that there was no significant difference in total 

abundance counts between a ROV and a research diver, and the ROV may have actually outperformed 

the divers, because of the divers' tendency to overestimate the size of objects. Raw data may be 

collected at speeds comparable to or exceeding that of divers, averaging between 0.14m and 0.6m per 

second (Pacunski et al. 2008). 

Images from ROVs may be analyzed both quantitatively and qualitatively for fauna greater than 1cm in 

diameter. While this may hinder the identification of small or cryptic species, larger fauna may be 

readily identifiable to at least a higher taxonomic level. In the Parry et al. (2003) study, the highest 

resolution of the ROV camera was 1.1mm +/- 0.1mm per pixel; that portion of the study was conducted 

in 2001 and resolution has improved since then. A unique strength of an ROV survey is that it allows 

the user to quickly generate percent cover, species presence/absence and count data without any need 

for rapid sample identification, preservation or live-dead assays. 

ROVs are costly and unwieldy to use. Leasing the equipment costs approximately $1000 per day (plus 

cost of crew); purchasing a small ROV costs between $10,000 and $100,000 dollars as a base price 

(Pacunski et al. 2008). Ancillary equipment, such as laser scaling systems, navigation systems, pressure 

sensors and flood lights can increase the price an additional $15,000-$150,000 (Pacunski et al. 2008). 

ROV technology also requires the availability of a skilled operator and maintenance personnel. 

Pacunski et al (2008) found that ROV technology is prone to mechanical, electrical, and software 
50

problems. Furthermore, the quality of data obtained appears to be directly related to the experience 

level of the operator, and biased estimates may result from differing fly-over heights or an uneven 

attitude towards the study surface (Pacunski et al 2008, Parry et al 2003). 

Diver Surveys 

Because of the combination of maneuverability and physical access, divers can deliver the highest 

resolution data in a variety of conditions. While ROVs are limited in feature dense or topographically 

complex areas of the hull, divers have the flexibility to access and collect from most areas of the hull, 

and to pinpoint and sample areas of special interest, such as sea-chests. Divers can also collect dense 

multi-layered organism assemblages and return samples to the surface where all the layers can be 

analyzed. Once brought to the surface and sorted, the sample can be identified to the species level for 

all taxa, including smaller mobile epifauna such as copepods and amphipods, and even for microscopic 

organisms. Organism viability (i.e. live/dead status) can be assessed either on site by divers or shortly 

after reaching the surface, which is not possible for ROV samples except in the most obvious cases. 

Diver surveys may be conducted in several ways. Godwin (2003) surveyed hulls using two divers that 

swam bow to stern on either side of a vessel, sampling each type of organism seen. Davidson et al 

(2006c) used a combination of randomized photo-quadrats and sample collections, with the surface 

team directing the divers via real-time audio and video feeds. Ruiz et al. (2005) surveyed in a nonrandom manner using divers with real-time audio and video feeds to the surface team, collecting all 

observed organisms along a transect and gathering presence/absence data from visual scans. In all of 

these cases, once samples were delivered to the surface they were rapidly processed by a team of 

biologists in a similar fashion. Samples were put on ice and transported back to the lab for sorting 

within a few hours of the original collection. Representative samples were then preserved and either 

identified to the lowest possible taxon on site, or sent to experts for further identification. The 

flexibility of diver surveys to use photo quadrats, specimen collections, and video transects allows the 

collection of a wide array of data including percent cover, presence/absence and abundance counts. 

Dive surveys, while yielding potentially large amounts of usable data, require considerable logistics 

before samples can be taken. Due to safety concerns, permission must be granted by port authorities, 

terminal operators and vessel operators prior to the start of the survey (Davidson et al 2006b). Further, 
51

the vessel's in-water activities must be altered for the duration of the survey, including turning off 

intake pumps, propellers, and electrolytic marine growth protection systems (Ruiz et al 2005). Before a 

survey is scheduled, availability of taxonomic experts will need to be arranged if immediate species 

identification and live-dead assays are to be conducted. Divers are subject to limitations when diving. 

Though depth would rarely be a concern for the majority of vessels, limitations such as time, air supply 

and surface connections (if applicable) would require several dives per surveyed vessel depending on 

its size (Davidson et al 2006c), and diver endurance would also affect the amount of work that could be 

conducted. This could translate into to a slower turnover time per vessel, as compared to ROV 

sampling, unless a team of four or more divers were used. 

Recommendations 

Analyzing shipping patterns provides an initial assessment of vessel types, routes, and voyage histories 

that are most likely to pose risks of introducing hull fouling NIS. This type of analysis can also 

identify individual ports that may be at more risk of receiving NIS. However, a more complete 

understanding of NIS risk requires more detailed studies of the biota on vessel hulls in order to “ground 

truth” the findings of the shipping pattern analyses. Because biotic surveys are labor and cost 

intensive, shipping pattern analyses can help to streamline the research by providing focal points on 

which to initially concentrate effort. Also, there are several levels of effort that can be applied to biotic 

surveys, with considerable differences in cost and quality/quantity of results. Here, referring to the 

previous section on sampling methods, we outline a multi-level and iterative study design that is 

intended to be cost effective and allow for continuously more focused and targeted studies 

The first level is an exploratory survey using archival video footage of from Under Water in Lieu of 

Drydock (UWILD) inspections to generate a broad understanding of the extent of fouling among 

vessels visiting Alaskan ports, and further identify potential areas of NIS risk, including areas on 

individual vessel hulls. The second level, which would be conducted on a narrower field of vessels, 

would use ROV or diver based video surveys. This step may be bypassed depending on the quality of 

data obtained in the first level. In addition, at either level one or two, visual rank assessment could be 

conducted on smaller vessels to provide general fouling patterns for that subset of vessels. The third 

level is a highly targeted series of diver based specimen collections to obtain high resolution species 

data. As previously mentioned, samples could also be taken while vessels are at drydock, but this 

would probably not yield representative samples, because most dry-docking of larger vessels is done 
52

overseas. 

Level one—Archived video 

For this level of study, archival UWILD video footage from vessels that arrive to Prince William Sound 

would be examined. To access these videos, permission to release the files must first be obtained from 

vessel owner/operators, and then requested from the libraries of the commercial diving companies that 

conducted the inspection surveys. Since the majority of vessel traffic to Prince William Sound arrives 

via the Pacific Northwest, several commercial dive companies in Oregon, Washington and British 

Columbia were contacted regarding their inspection services. These companies reported performing 

inspections on a wide array of large vessels, including tank ships, cruise ships, bulkers, container ships, 

large fishing vessels, Navy and Coast Guard vessels. Most commercial diving companies keep copies 

of all inspection videos for at least three years, while some companies may retain copies indefinitely. If 

the videos are numerous and extensive, viewing could be prioritized based on the risk criteria identified 

in the analysis of the SANS data base provided in this report. The videos may then be analyzed for 

percent cover and presence/absence of organisms at broad taxonomic levels. Videos must contain 

enough footage to sufficiently cover all parts of a vessel’s underwater surfaces. We recommend that a 

set number of quadrats from still frames be conducted randomly on the hull, along with semi-random 

quadrats on non-hull surfaces, if possible. Because non-hull surfaces may act as a refuge for fouling 

organisms, these areas may warrant special focus. If videos are high enough quality, some quantitative 

measures of biota can be made. For example, Coutts and Taylor (2004) assessed taxa richness and 

percentage cover for each quadrat by estimating the size of the image, and using 50 random points 

superimposed over the video monitor. Taxa richness and percentage cover data were then analyzed 

using statistical methods such as general linear mixed models, pair-wise comparisons of means, and 

multivariate analyses, with “vessel type” and “hull location” as fixed factors. 

The factors that should be evaluated after video is obtained and reviewed are: 

• Is the range of vessel types and ports adequate to answer the questions being asked? 

• Is the resolution high enough to identify fouling patterns? 

• Do videos of individual vessel hulls adequately cover the hull surface? 

In the best case, if enough adequate footage is found, this level would yield information on the extent 

of biofouling across a large subset of vessels arriving to Prince William Sound. It would likely not, 
53

however, provide useful information on specific NIS. If the data obtained at this level is deemed 

sufficient for the purposes of the study, the study may be restricted to only archival video analysis. If 

higher species resolution is desired, data from the level one archival footage should be evaluated to 

determine if it supplies enough information to detect fouling patterns associated with vessel types, 

voyage types, etc. If such a pattern is evident and appears representative, hull fouling studies may 

proceed to level three, where a smaller more focused study can be done by divers. If meaningful 

patterns cannot be detected due to limitations of the archived video, the study may proceed to level 2, 

where directed video may be obtained by divers or an ROV. 

Level two—ROV and diver video surveys 

ROV and diver video surveys offer a step up from UWILD video in that there is more ability to control 

what is sampled. Sampling can be targeted at ports, vessel types, or voyage types of interest, and 

specific areas on an individual vessel hull can also be targeted. At this level, researchers may use either 

divers with video feeds or an ROV to conduct directed video surveys. The control afforded by this 

method allows vessels to be directly compared in a uniform manner. We recommend the divers or ROV 

perform several transects along the length of a vessel's hull, followed by special attention to supportblock strips and non-hull areas where fouling may accumulate (forward of propellers, rudder, bilge 

keels, sea-chest grating, etc). A real-time video feed may also be viewed by biologists who can identify 

areas to be sampled (see level three). During post-processing of videos taken at this level, videos can 

be paused at both random points and targeted focal points to obtain percent cover and presence/absence 

of organisms at broad taxonomic levels. This data may then be analyzed statistically using general 

linear models, multivariate analyses, pair-wise comparisons of means (e.g., Coutts and Taylor 2004) 

and analysis of similarities (ANOSIM) (Davidson et al 2009). 

Level two sampling would allow more controlled data to be gathered on the extent and location of 

biofouling across a range of vessels, but as with level one sampling, would not provide much 

information on specific NIS. However, the likelihood of level two sampling providing meaningful data 

that would help to target level three sampling is likely higher than that obtained with level one 

sampling. 

Level three—targeted biological sampling by divers 

After level one and two analyses, targeted biological sampling can be conducted on vessels of interest. 
54

This sampling could also be done in conjunction with level two sampling, if it is conducted by divers. 

This method is the most complicated with respect to access, safety, and time considerations, and is the 

most labor and cost-intensive method. Thus, level three sampling might best be conducted by 

strategically narrowing the subset of vessels to be sampled to those that are hypothesized to be high 

risk vectors, as determined by level one and two sampling. For this level of sampling, divers would 

collect representative samples of fouling observed along transects on vessel hulls. Biofouling would 

also be visually assessed as in level two. If budgets allow, divers could be connected via live video with 

biologists that could direct targeted sampling. Transects could be saved as video files and analyzed 

extensively. The samples can be rapidly assessed while alive. However, most species identifications 

would be done from samples that are fixed and sent to taxonomic experts. 

Level three sampling yields high resolution information on specific fouling organisms and potential 

and known NIS found in hull samples. Percent cover can also be obtained, though due to limitations in 

the time divers can spend in the water, this data may be limited to only portions of a vessel. To analyze 

species composition, a presence/absence matrix is generated using voucher specimens. Post-processing 

of percent cover data is accomplished by the point count method of superimposing 100 random dots 

over each quadrat. Statistical methods that can be used to analyze the species composition and 

percentage cover data include univariate analysis, multivariate analysis, analysis of similarities 

(ANOSIM), and an accumulation curve to provide an indication of whether all species present were 

likely sampled (Davidson et al 2006c). 
55

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Appendix Table 1. Voyage histories of vessels entering Alaskan ports of interest, 2005-2008. NW = 

Pacific northwest of United States + British Columbia, SF = San Francisco Bay area, S. CA = southern 

California. 

2005 2006

Total 814 Total 617

Asia 39 Asia 39

Japan 15 Japan 21

South Korea 12 South Korea 9

China 4 China 6

Russia 4 Russia 14

Malaysia 2 Malaysia 1

India 2 India 0

Singapore 19 Singapore 9

Vietnam 1 Vietnam 0

NW 574 NW 404

Oregon 39 Oregon 15

Puget Sound 390 Puget Sound 253

British Columbia 195 British Columbia 160

SF 195 SF 142

S.CA 113 S.CA 100

S. Pacific 14 S. Pacific 15

Other 7 Other 11

Mexico 10 Mexico 24

 

2007 2008

Total 578 Total 575

Asia 32 Asia 28

Japan 20 Japan 11

South Korea 8 South Korea 6

China 7 China 8

Russia 10 Russia 7

Malaysia 3 Malaysia 0

India 1 India 1

Singapore 2 Singapore 11

Vietnam 0 Vietnam 0

NW 460 NW 453

Oregon 13 Oregon 19

Puget Sound 136 Puget Sound 280

British Columbia 153 British Columbia 179

SF 160 SF 163

S.CA 108 S.CA 83

S. Pacific 24 S. Pacific 25

Other 19 Other 24

Mexico 32 Mexico 31
Appendix Table 2. Number of arrivals to Alaskan ports of interest 2005-2008 by vessel type. 

2005 Cape Hinchinbrook College Fjord Cordova Kodiak PWS Seward Valdez Whittier Tatilek 

Fishing 0 0 2 30 4 2 5 2 0 Freight 0 0 0 81 2 9 4 1 0 Passenger 0 16 6 15 1 60 11 78 6 Tank 16 0 0 0 7 0 382 0 0 Towing 0 0 4 10 0 4 12 41 0 Other 0 0 0 2 0 0 0 0 0 Grand Total 16 16 12 138 14 75 414 122 6 

2006 Cape Hinchinbrook College Fjord Cordova Kodiak PWS Seward Valdez Whittier Tatilek 

Fishing 0 0 4 36 4 5 1 2 0 Freight 0 0 0 43 2 8 3 0 0 Passenger 0 0 2 10 1 43 1 69 0 Tank 1 0 0 0 9 0 312 1 0 Towing 0 0 1 4 0 5 5 35 0 Other 0 0 1 3 0 3 0 0 0 Grand Total 1 0 8 96 16 64 322 107 0 

2007 Cape Hinchinbrook College Fjord Cordova Kodiak PWS Seward Valdez Whittier Tatilek 

Fishing 0 0 3 18 7 5 0 0 0 Freight 0 0 0 45 2 4 5 0 0 Passenger 0 0 0 4 0 56 0 64 0 Tank 6 0 0 0 3 1 296 0 0 Towing 0 0 1 5 0 5 7 34 0 Other 0 0 0 3 0 0 0 0 0 Grand Total 6 0 4 75 12 71 308 98 0 

2008 Cape Hinchinbrook College Fjord Cordova Kodiak PWS Seward Valdez Whittier Tatilek 

Fishing 0 0 3 23 8 1 3 1 0 Freight 0 0 1 40 2 9 1 1 0 Passenger 0 1 0 12 0 66 8 50 0 Tank 0 0 0 0 0 0 282 0 0 Towing 0 0 1 5 0 1 5 35 0 Other 0 0 0 1 1 4 0 0 0 Grand Total 0 1 5 81 11 81 299 87 0 
62

Appendix Table 3. Voyage types of arrivals by port, 2005-2008, for vessels entering Alaskan ports of 

interest, 2005-2008. 

Voyage Type by Port

2005 Domestic Other Total WC Total Transp Grand Total

Cape Hinchinbrook 2 0 13 1 16

College Fjord 1 0 15 0 16

Cordova 9 0 3 0 12

Kodiak 70 0 45 7 122

Prince William Sound 1 0 12 1 14

Seward 9 1 55 11 76

Valdez 29 0 335 27 391

Whittier 16 0 104 2 122

Tatilek 1 0 5 0 6

Total Result 138 1 587 49 775

 

2006 Domestic Other Total WC Total Transp Grand Total

Cape Hinchinbrook 0 0 1 0 1

College Fjord 0 0 0 0 0

Cordova 5 0 2 1 8

Kodiak 64 0 21 11 96

Prince William Sound 4 0 12 0 16

Seward 15 2 39 7 63

Valdez 34 1 266 16 317

Whittier 2 0 94 11 107

Tatilek 0 0 0 0 0

Total Result 124 3 435 46 608

 

2007 Domestic Other Total WC Total Transp Grand Total

Cape Hinchinbrook 0 0 6 0 6

College Fjord 0 0 0 0 0

Cordova 3 0 0 1 4

Kodiak 51 0 17 7 75

Prince William Sound 6 0 6 0 12

Seward 4 3 52 13 72

Valdez 6 1 288 11 306

Whittier 6 0 76 16 98

Tatilek 0 0 0 0 0

Total Result 76 4 445 48 573

 

2008 Domestic Other Total WC Total Transp Grand Total

Cape Hinchinbrook 0 0 0 0 0

College Fjord 0 1 0 0 1

Cordova 3 0 2 0 5

Kodiak 55 1 20 5 81

Prince William Sound 5 1 5 0 11

Seward 3 2 60 16 81

Valdez 8 0 275 16 299

Whittier 3 0 76 8 87

Tatilek 0 0 0 0 0 

Total Result 77 5 438 45 565
63

Appendix Table 4. Voyage types of incoming arrivals by vessel type, 2005-2008, for vessels entering 

Alaskan ports of interest, 2005-2008. 

 Voyage Types 

2005 Other Fishing Freight Passenger Tank Towing Total 

Domestic 0 30 31 43 19 14 137

Other 0 0 0 1 0 0 1

Total Transp 2 0 15 7 23 2 49

Total WC 0 14 37 142 340 55 588

Total Result 2 44 83 193 382 71 775

 

2006 Other 

Fishing 

Boat 

Freight 

Ship Passenger Tank Ship 

Towing 

vessel Total 

Domestic 0 33 36 14 32 9 124

Other 0 0 1 1 1 0 3

Total Transp 4 1 11 18 12 0 46

Total WC 3 20 5 93 273 41 435

Total Result 7 54 53 126 318 50 608

 

2007 Other 

Fishing 

Boat 

Freight 

Ship Passenger Tank Ship 

Towing 

vessel Total 

Domestic 0 16 48 6 5 1 76

Other 0 0 0 1 0 3 4

Total Transp 2 0 10 23 8 4 47

Total WC 1 14 1 94 291 44 445

Total Result 3 30 59 124 304 52 572

 

2008 Other 

Fishing 

Boat 

Freight 

Ship Passenger Tank Ship 

Towing 

vessel Total 

Domestic 0 20 44 2 5 6 77

Other 2 0 0 3 0 0 5

Total Transp 3 0 10 19 13 0 45

Total WC 1 17 2 113 264 41 438

Total Result 6 37 56 137 282 47 565
64

Appendix Table 5. Voyage history of incoming arrivals to Alaskan ports of interest 2005-2008 by vessel 

type. 

Voyage history per year by ship type 

2005 Fishing Freight Passenger Tank Towing Other Total 

Asia 0 15 7 14 2 1 39 

NW 14 42 146 312 58 0 572 

SF 0 0 4 191 0 0 195 

S. CA 0 0 6 107 0 0 113 

South Pacific 0 0 1 12 0 1 14 

Other 0 3 4 0 0 0 7 

Mexico 0 1 9 0 0 0 10 

 

2006 Fishing Freight Passenger Tank Towing Other Total 

Asia 1 12 14 9 0 3 39 

NW 15 5 109 233 42 2 406 

SF 0 0 1 141 0 0 142 

S. CA 0 2 0 98 0 0 100 

South Pacific 1 2 5 4 0 3 15 

Other 0 3 3 1 0 2 9 

Mexico 0 1 20 1 0 2 24 

 

2007 Fishing Freight Passenger Tank Towing Other Total 

Asia 0 10 14 4 0 2 30 

NW 11 3 116 276 46 1 453 

SF 0 0 0 158 2 0 160 

S. CA 0 0 0 108 0 0 108 

South Pacific 0 0 12 4 4 2 22 

Other 1 1 8 0 4 1 15 

Mexico 0 0 28 0 3 1 32 

 

2008 Fishing Freight Passenger Tank Towing Other Total 

Asia 0 9 10 9 0 0 28 

NW 10 4 132 255 42 4 447 

SF 1 0 0 162 0 0 163 

S. CA 0 0 0 80 0 2 82 

South Pacific 0 4 11 6 1 3 25 

Other 0 4 12 0 4 3 23 

Mexico 0 1 27 0 0 2 30 
Appendix Table 6. Distribution of fouling organisms outside their native ranges. Organisms notated with a ‘B’ are primarily benthic/epibenthic species that have been associated with hull fouling in Washington, OR=Oregon, HB= Humboldt Bay, Socal= Southern California, Chspk= Chesapeake Bay, NE-US=Norof Mexico, AU= Australia, HI= Hawaii, MED= Mediterranean, Neuro= Northern Europe, BC= British Columbia, A

WA OR HB Socal SF Chspk NE-US Gmex AU HI 

Ascidians Botrylloides violaceus x x x x x x x Ascidians Botryllus schlosseri x x x x x x x x Ascidians Ciona savignyi x x x x Ascidians Didemnum vexillum x x x x x Ascidians Molgula manhattensis x x x x x x x Ascidians Styela clava x x x x x x x Bryozoans Bugula stolonifera x x x x x Bryozoans Watersipora subtorquata x x x x x x Byrozoans Bowerbankia gracilis x x x x x x x Byrozoans Bugula neritina x x x x x x x x x x Byrozoans Conopeum tenuissimum x x Byrozoans Cryptosula pallasiana x x x x x x Byrozoans Schizoporella unicornis (japonica) x x x x x x x x Sponges Halichondria bowerbanki x x x Sponges Haliclona spp x x x Sponges Microciona (Clathria) prolifera x x x Cnidarians- Anthozoans Diadumene cincta x x Cnidarians-anthozoan Diadumene leucolena x x x x Cnidarians-anthozoan Diadumene lineata x x x x x x x x Cnidarians-hydrozoans Blackfordia virginica x x x x Cnidarians-hydrozoans Cladonema radiatum x Cnidarians-hydrozoans Cordylophora caspia x x x x x x x Cnidarians-hydrozoans Ectopleura (tubularia) (pinauay) crocea x x x x x x Cnidarians-hydrozoans Garveia franciscana x x x 
WA OR HB Socal SF Chspk NE-US Gmex AU HI 

Entoprocta Barentsia benedeni x x x x x x Foraminiferans Trochahammina hadai x x Mollusc-bivalvia Mytilus edulis x Mollusc-bivalvia Mytilus galloprovincialis x x x x x x Molluscs-bivalvia Teredo navalis x x x x x 

B Molluscs-gastropods Myosotella myosotis x x x x x x x B Molluscs-nudibranch Tenellia adspersa x x x x B Polychaetes Heteromastus filiformis x x x x x x B Polychaetes Neanthes succinea x x x B Polychaetes Polydora cornuta x x x x x x x B Polychaetes Pseudopolydora kempi x x x x x x B Polychaetes Pseudopolydora paucibranchiata x x x x x x B Polychaetes Streblospio benedicti x x x x x x B Arthropods-Amphipods Ampithoe valida x x x x x x B Arthropods-Amphipods Caprella mutica x x x x x B Arthropods-Amphipods Chelura terebrans x x x x B Arthropods-Amphipods Incisocalliope (Parapleustes) derzhavini x x x x B Arthropods-Amphipods Jassa marmorata x x x x x x B Arthropods-Amphipods Melita nitida x x x x x B Arthropods-Amphipods Monocorphium acherusicum x x x x x x x x B Arthropods-Amphipods Monocorphium insidiosum x x x x x x x B Arthropods-barnacles Balanus improvisus x x x B Arthropods-decapods Rhithropanopeus harrisii x x B Arthropods-Isopods Iais californica x x x x x B Arthropods-Isopods Limnoria quadripunctata x x B Arthropods-isopods Limnoria tripunctata x x x x B Arthropods-Isopods Sphaeroma quoyanum x x x x B Arthropods-isopods Synidotea laevidorsalis x x x x B Arthropods-Tanaids Sinelobus stanfordi x x x x x x 

Sources: National Introduced Pest Information System (CSIRO), National Benthic Inventory (NOAA), North Europe

on Invasive Alien Species (NOBANIS), National Exotic Marine and Estuarine Species Information System (SERC), N
Species (USGS), Guidebook of Introduced Marine Species of Hawaii (Hawaii Biological Survey), Non-native Aquat

Mexico and South Atlantic Regions (Gulf State Marine Fisheries Commission), Atlas of Exotic Species in the MediteFact Sheet (PWSRCAC), Ashton et al (2008), Boyd et al (2002), Cohen (2004), Cohen & Carlton (1995, 1998), Coh2002, 2005a, 2005b, 2005c), Hines & Ruiz (2000), McGee et al (2006), Ray (2005) (ANSRP), Ruiz et al (2006), Won
Appendix Table 7. Anti-fouling paints used and hull locations where applied.

ReportYear Vessel Name Manufacturer Antifouling Product Name Biocide1 Biocide2

Hull 

Sides

Hull 

Bottom

Sea 

Chests

Sea 

Chest 

Gratings Propeller

Rope 

Guard 

Propeller 

Shaft

Previ

Dock

Bloc

2008 ALASKAN EXPLORER International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE FAL

2009 ALASKAN EXPLORER International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE FAL

2008 ALASKAN FRONTIER International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE FAL

2009 ALASKAN FRONTIER International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE FAL

2008 ALASKAN LEGEND International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE FAL

2009 ALASKAN LEGEND International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE FAL

2008 ALASKAN NAVIGATOR International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE FAL

2009 ALASKAN NAVIGATOR International Paint Ltd. Interclene 245 Cuprous Oxide Zineb TRUE TRUE TRUE TRUE FALSE TRUE FAL

2009 CAPTAIN H. A. DOWNING Jotun Paints Hydroclean (AKA SeaGuardian) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE FALSE TR2008 KODIAK International Paint Ltd.

Interspeed 340 (BQA 341-344, 346, 347, 349) Cuprous Oxide Zineb TRUE FALSE TRUE TRUE FALSE TRUE FAL

2009 KODIAK International Paint Ltd.

Interspeed 340 (BQA 341-344, 346, 347, 349) Cuprous Oxide Zineb TRUE FALSE TRUE TRUE TRUE FALSE TR

2008 MISSISSIPPI VOYAGER International Paint Ltd. Interspeed 640 (BRA 640-644) Cuprous Oxide TRUE TRUE FALSE FALSE FALSE TRUE TR2009 MISSISSIPPI VOYAGER International Paint Ltd. Interspeed 640 (BRA 640-644) Cuprous Oxide TRUE TRUE TRUE TRUE TRUE TRUE TR

2009 OVERSEAS NEW YORK Chugoku Marine Paint Sea Grandprix 500, 500M Cuprous Oxide

Copper Pyrithione TRUE TRUE TRUE TRUE FALSE FALSE FAL

2008 POLAR ADVENTURE International Paint Ltd. Intersleek (none specified) Biocide-free Silicone TRUE TRUE TRUE TRUE TRUE TRUE TR2008 POLAR DISCOVERY International Paint Ltd. Intersleek (none specified) Biocide-free Silicone TRUE TRUE TRUE TRUE TRUE TRUE TR2009 POLAR DISCOVERY International Paint Ltd. Intersleek 757

Biocide-free Silicone topcoat TRUE TRUE TRUE TRUE TRUE TRUE TR

2008 POLAR ENDEAVOUR International Paint Ltd. Intersleek (none specified) Biocide-free Silicone TRUE TRUE TRUE TRUE TRUE TRUE TR

2009 POLAR ENDEAVOUR International Paint Ltd. Intersleek 757

Biocide-free Silicone topcoat TRUE TRUE TRUE TRUE FALSE TRUE TR

2008 POLAR ENTERPRISE International Paint Ltd. Intersleek (none specified) Biocide-free Silicone TRUE TRUE TRUE TRUE TRUE TRUE TR

2009 POLAR ENTERPRISE International Paint Ltd. Intersleek 757

Biocide-free Silicone topcoat FALSE TRUE TRUE TRUE FALSE TRUE TR

2008 POLAR RESOLUTION International Paint Ltd. Intersleek 757

Biocide-free Silicone topcoat FALSE TRUE TRUE TRUE FALSE TRUE TR

2009 POLAR RESOLUTION International Paint Ltd. Intersleek 757

Biocide-free Silicone topcoat TRUE TRUE TRUE TRUE FALSE FALSE FAL

2008 S/R BAYTOWN International Paint Ltd. Intersleek 737

Biocide-free Silicone intermediate coat TRUE TRUE TRUE TRUE TRUE TRUE TR

2009 S/R BAYTOWN International Paint Ltd. Intersleek 737

Biocide-free Silicone intermediate coat TRUE TRUE TRUE TRUE TRUE TRUE TR

2008 S/R LONG BEACH International Paint Ltd.

Interspeed 340 (BQA 341-344, 346, 347, 349) Cuprous Oxide Zineb TRUE FALSE TRUE TRUE FALSE TRUE FAL

2009 S/R LONG BEACH International Paint Ltd.

Interspeed 340 (BQA 341-344, 346, 347, 349) Cuprous Oxide Zineb TRUE FALSE TRUE FALSE FALSE FALSE FAL

2008 SEABULK ARCTIC International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE FALSE TR

2009 SEABULK ARCTIC International Paint Ltd. Interspeed 340 Cuprous Oxide Zineb TRUE FALSE FALSE FALSE FALSE FALSE FAL2008 SEABULK PRIDE International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE FALSE TR2009 SEABULK PRIDE International Paint Ltd. Interclene 245NA (BRA570, 572) Cuprous Oxide TRUE TRUE TRUE TRUE FALSE TRUE TR

2008 SIERRA International Paint Ltd.

Interspeed 340 (BQA 341-344, 346, 347, 349) Cuprous Oxide Zineb TRUE FALSE TRUE TRUE FALSE TRUE FAL

2009 SIERRA International Paint Ltd. Intersleek 900

Biocide-free fluoropolymer TRUE FALSE TRUE TRUE TRUE FALSE TR