CONSUMPTION OF FRESHWATER FISH

BY MAINE ANGLERS

R E Keenan

Chief Health Scientist

McLarenHart

ChemRisk®

Portland Maine

USA

J W Knight

Environ Scientist

McLarenHart

ChemRisk®

Portland Maine

USA

ABSTRACT

E S Ebert

Senior Health Scientist

McLarenHart

ChemRisk®

Portland Maine

USA

N W Harrington

Environ Scientist

McLarenHart

ChemRisk®

Portland Maine

USA

In deriving a water quality standard that is protective

of human health it is essential that realistic estimates

of exposure be used For lipid soluble chemicals

like 2378tetrachlorodibenzopdioxin the most

important potential route of human exposure is

through direct ingestion of fish Historically it has

been stated that recreational anglers incur the greatest

potential for exposure due to their presumed high

levels of fish consumption However a number of

site specific factors including species preference

availability access length of fishing season and

cultural heritage can greatly influence rates of

freshwater fish consumption within a single region

of the United States It is inappropriate to generalize

by applying a fish consumption estimate from one

region of the country to another region for the

purpose of deriving state specific water quality

regulations as there is a potential to severely

overestimate or underestimate actual rates of

consumption To avoid this deficiency a statewide

mail survey was undertaken to characterize current

rates of freshwater fish consumption by Maines

resident recreational anglers Results of the survey

indicate that consumption of freshwater fish is

considerably lower in Maine than has been reported

for other regions of the country Findings of the

study confirm that state or region specific estimates

of fish consumption should be developed for use in

establishing water quality regulations that are based

on the protection of human health

KEY WORDS

2378TCDD dioxin fish consumption water

quality

INTRODUCTION

In recent years a number of states have derived

ambient water quality standards for 2378

tetrachlorodibenzopdioxin TCDD using EPAs

1984 default value of 65 gday for fish

consumption This value used by the EPA 1984

in developing its Ambient Water Quality Criteria for

TCDD is a national per capita fish consumption rate

which includes all commercially harvested and

recreationallycaught freshwater and estuarine fish

and shellfish EPA 1989a While this consumption

rate may be reasonable for certain regions of the

counts where TCDD affects commercial freshwater

and estuarine fisheries from which fish are harvested

for distribution to the general population it is not an

appropriate rate for states in which there are no

commercial fisheries on impacted inland waters

In the state of Maine TCDD has only been detected

in fish tissues collected from certain non estuarine

reaches of a few warmwater rivers in the state

Because Maine has no commercial fisheries on the

rivers potentially impacted fish are not available to

the general population but rather are only available

to anglers who fish these waters and those

individuals who share in their harvest Because this

was the only population potentially impacted by fish

from these rivers it was believed that a region or

state specific estimate of consumption of freshwater

fish from rivers should be used a the basis for a

water quality standard for TCDD in Maine

Published studies that specifically investigate or

estimate freshwater fish consumption in Maine are

nonexistent The fish consumption data that are

available in the scientific literature are based on

national surveys or are specific to other regions of

the country Rupp et al 1980 Humphrey 1978

Parsons et al 1991 Puffer et al 1981 Pierce et

al 1981 Javitz 1980 Honstead et al 1971

Many surveys make no distinction between the

consumption of commercially harvested and

recreationally harvested fish Javitz 1980 EPA

1989a The most frequently used estimates of fish

consumption are of limited use for estimating

freshwater fish consumption from Maine rivers

because they are either based on marine studies

Puffer et al 1981 Pierce et al 1981 or include a

1992 Environmental Conference 895

EPA001542
combination of both saltwater and freshwater species

and do not consider the sources of the fish

consumed in the diet Javitz 1980 EPA 1989a

Furthermore the use of freshwater fish consumption

studies from one region of the US may

overestimate or underestimate the consumption of

freshwater fish in another region of the country as

differences in preferred species availability access

length of fishing season and cultural heritage can

greatly influence freshwater fish consumption in a

particular region

Due to lack of relevant data pertaining to

consumption of freshwater species from rivers in

Maine or the northeastern United States a statewide

mail survey of licensed resident anglers was

undertaken The purpose of this study was to

characterize the rates of freshwater fish consumption

by Maines resident anglers This study was

modeled after earlier surveys conducted on behalf of

the Maine Department of Inland Fisheries and

Wildlife IFW Boyle et al 1989 These IFW

surveys assessed angler effort The present

investigation was designed to determine what

amount and proportion of the fish catch harvested

from Maines inland waters is consumed daily by

licensed anglers

METHODS

Survey design and implementation

A statewide mail survey was developed with the

assistance of HBRS in Madison Wisconsin

resource economists at the University of Maine and

fisheries biologists with IFW A pretest of the

survey was conducted in order to evaluate whether

respondents had difficulty in understanding or

responding to any of the survey questions Based

on responses gathered in telephone interviews in the

pretest and a review of the returned pretest surveys

final revisions to the survey were made

The sample population consisted of Maine residents

holding a valid Maine fishing license in 1989 A

total of 2500 surveys were mailed to Maine resident

anglers whose names were randomly selected from

the 1989 license files of IFW Because IFW license

files for 1990 were incomplete at the time that the

sample was selected names were randomly selected

from the complete 1989 IFW files of resident fishing

licenses As open water fishing season for most

Maine waters closes September 30 surveys were

mailed in midOctober of 1990 Postcards were sent

one week later thanking those who had already

returned the survey and asking those who had not

yet returned the survey to do so On November 7

1990 a followup survey packet was mailed to

1111 anglers who had not yet responded and the

recipients were asked to complete and return the

survey by December 3 1990

Data Analysis

A numerical coding scheme was used to record

responses to each question in the mail survey Each

returned survey was translated to numeric values

and edited and the numeric values were then entered

into a data base using the SPSSPC V31 + Data

Entry II Program SPSS 1989 To verify that all

data were entered correctly each completed survey

was entered twice and the results compared

Response frequencies were constructed for each

survey question as a final check for data entry

accuracy

Anglers were asked to report the number of each

species of fish caught during the 19891990 ice

fishing season and 1990 open water season For

those fish caught during open water season anglers

were asked to report and differentiate between fish

obtained from standing waters lakes and ponds and

those obtained from flowing waters rivers and

streams Of the total fish caught anglers were

asked to estimate the total number of fish and the

average length of each fish that was eventually

consumed In addition to those fish caught by the

responding angler the respondents were also asked

to describe the number species and average length

of each consumed fish which was obtained from

other members of the respondents household and

from individuals outside of the household

For analytical purposes the population of interest

was defined as all respondents who fished in either

the 19891990 ice fishing or 1990 open water

fishing seasons and all respondents who did not

fish in either season but consumed Maine

freshwater fish caught by either another member of

the respondents household or by someone outside

the respondents household Respondents were also

asked to report the number of other freshwater fish

consumer living in the respondents household

The ice fishing season may include the end of one

calendar year and the beginning of the next calendar

year As it was believed that ice fishermen would

likely recall the season as a whole rather than just

896 TAPPI Proceedings

EPA001543
that portion occurring in 1990 anglers were asked

about the entire 19891990 ice fishing season It

was assumed that the frequency and success of ice

fishing trips in the late Fall and early Winter of 1989

would be representative of trips to be taken in the

late Fall and early Winter of 1990 Therefore to

avoid duplication anglers were not asked to estimate

ice fishing trips planned for the late Fall of 1990

Because some Maine waters are open for limited

fishing until October 31 respondents were asked

whether they planned to make any additional open

water fishing nips between the date of completion of

the survey and the end of October a period of no

more than two weeks If they did plan future trips

they were asked to indicate how many future trips

were planned

Each respondent was asked to report how many

fishing trips had been made to ice fishing standing

water and flowing water locations during the

season The total number of reported trips was

calculated for each angler as was the ratio of trips to

flowing waters to trips to standing waters and ice

fishing locations Future consumption from all

waters and from flowing waters was estimated by

assuming that consumption from future trips would

be directly proportional to reported consumption

from completed trips

Estimating Fish Consumption Rates

The total mass of freshwater fish consumed by each

respondents household was estimated from the

respondent provided information on quantity and

average length of each consumed fish species For

example the equation used to estimate the mass of

freshwater fish consumed from ice fishing sources is

presented below

IMC = QI x 10tCi + n log LI x 0 x EP

where

1MC = Total mass of freshwater fish

species i consumed by angler

and household from Maine ice

fishing sources g

QI = Quantity of fish species i

consumed from Maine ice

fishing sources

C = Constant in lengthmass

relationship for species i log

g

ni

LI

EP =

Slope in lengthmass relationship

for species i log glog mm

Average length of consumed

freshwater fishspecies i from Maine

ice fishing sources in

conversion factor 254 mmin Fraction of whole fish mass that is

edible for species i g consumedg

whole fish

For each fish species the mass of each fish was

estimated from the lengths reported by each angler

using a standard length to mass relationship

expressed as a linear regression based on logarithms

Nielsen and Johnson 1983 Cone 1989

log W = C + n Log L

The parameters C and n are species specific

constants The exact value of n is dependent on the

shape of the fish however it usually approximates 3

Nielsen and Johnson 1983 The exact value of

each parameter is affected by several variables

including season the type of waterbody in which the

fish resides the sex age and sexual maturity of the

fish Because these parameters can vary widely the

relationship for a particular species in a given river

lake or stream is most precisely determined by site

specific sampling and measurement

For several species constants relating length to mass

were taken from logarithmic regression equations

specific to the state of Maine These constants were

obtained from IFW and were derived from length

and mass measurements compiled over several years

from numerous Maine rivers and lakes For those

species for which Maine specific equations were not

available the most appropriate relationship was

selected from those reported in the available literature

Carlander 1969 1977

Using the length mass relationship yields the mass

of the whole fish based on its length Because not

all of the fish is edible it was necessary to

characterize the relationship between the mass of a

whole fish and that portion considered to be edible

The EPA 1989b recommends that 30 percent be

used to estimate the edible portion of finfish

Specific studies were undertaken to determine the

edible portion of smallmouth bass and landlocked

salmon in Maine Ebert 1991a In these Maine

studies the edible portion was defined as being

synonymous with fillet size Although it is

recognized that a number of fish species may not be

1992 Environmental Conference 897

EPA001544
filleted overall the use of fillet data is a reasonable

estimator for the edible portion of the fish

For smallmouth bass collected from two Maine

rivers the mean edible portion was approximately

30 percent of the whole fish mass Ebert 1991a

Landlocked salmon demonstrated a mean edible

portion of 37 percent Ebert 1991a Based on

recommendations by EPA 1989b and the results of

the Maine specific studies Ebert 1991a

conservative edible portions of 40 percent for

landlocked salmon and Atlantic salmon and 30

percent for all other species except smelt were

selected to estimate consumable mass For smelt a

higher edible portion estimate of 78 percent was

used Selection of this higher multiplier was based

on the knowledge that some smelt consumers eat all

but the head of the fish while others do not eat the

viscera or the head Data on the relative weight of

head and viscera as recorded during the analyses of

landlocked salmon edible portion Ebert 1991b

were used to estimate the edible portion for smelt

The freshwater fish mass consumed from Maine ice

fishing sources by the angler and his or her

household was then calculated as the sum of IMCi

over the fifteen species Analogous equations were

developed for calculating consumption from lakes

and ponds rivers and streams other household

sources and non household sources based on

reported quantities and lengths of fish consumed

from each of these sources

For those 88 respondents indicating that future

fishing trips were planned the freshwater fish

consumption rate from these future trips was

estimated on the plausible assumption that

consumption of fish from future trips would be

proportional to consumption from trips already

completed and reported

The average daily freshwater fish reported

consumption rate from all Maine sources for

individual members of a respondents household

was computed by summing the source specific and

computed future mass of fish consumed and then

dividing by household size using the following

equation

FCA = IMCT + SMCT + FMCT +

HMCT + OMCT + MCF x

1HS x 1T

where

FCA =

IMCT =

SMCT =

FMCT =

HMCT =

OMCT =

MCF =

HS =

T=

Freshwater fish consumption from

all Maine sources gpersonday

Total mass of freshwater fish

consumed from Maine ice fishing

sources g Total mass of freshwater fish

consumed from Maine standing

water sources g Total mass of

consumed from

water sources g Total mass of

consumed from

sources g Total mass of freshwater fish

consumed from other non

household Maine sources g Total mass of freshwater fish

estimated to be consumed from

future fishing trips g

Number of persons in anglers

household reported to consume

freshwater fish persons

Time over which fish was

consumed 365 days

freshwater fish

Maine flowing

freshwater fish

other household

Household size was calculated as the number of

persons in the anglers household who were

reported to eat the freshwater fish caught The mass

of fish consumed per household member was then

divided by 365 days to yield an annualized per

person perday fish consumption estimate

Estimates of freshwater fish consumption from

flowing water only were computed using a similar

method Future consumption attributable to flowing

waters was estimated by multiplying the future

consumption estimated for all sources by the ratio of

the number of fishing trips reported for flowing

waters to the total number of fishing trips reported

The portion of consumption from other household

and non household sources attributable to flowing

waters was estimated based on the ratio of reported

consumption from flowing water to reported

consumption from ice fishing standing water and

flowing water combined

RESULTS

A total of 1612 surveys were completed and

returned Of these 1369 reported having fished

during the 198990 ice fishing season or the 1990

898 TAPPI Proceedings

EPA001545
open water season or having consumed Maine

freshwater fish caught during the 19891990 season

A total of 1251 respondents reported having fished

during either the ice fishing season or the open water

season or both Of the 599 individuals who

indicated that they had gone ice fishing 508 85

percent reported having caught fish Of the 1127

individuals who went open water fishing 1053

reported having fished in ponds or lakes and 745

reported having fished in streams and rivers A total

of 976 individuals 87 percent reported having

caught fish on at least one open water fishing trip

during the 1990 season While 352 respondents did

not fish in either season 109 of these did consume

freshwater fish from other Maine sources These

109 respondents with the 1251 who fished in 1989

90 made up the 1369 anglers defined as the

population of interest

Due to the large sample size statistical analysis was

conducted without assuming a distributional model

Table 1 presents the median 50th percentile 66th

75th 90th and 95th percentiles which were

calculated by rank to summarize fish consumption

rates

Consumption of fish caught in all types of

waterbodies including lakes ponds streams and

rivers is designated as All Waters whereas

consumption of fish from flowing waters only is

designated as Rivers and Streams Within the All

Waters category there are two subgroups

identified All Anglers representing the total

respondent population of interest and their

households including non consumers and

Consuming Anglers representing fishconsuming

angler households only In addition to the All

Anglers and Consuming Anglers designations

within the Rivers and Streams category a third

subgroup was identified This group designated as

River Anglers includes survey respondents

consumers and non consumers who indicated that

they fished on rivers or streams at least once during

the 1990 open water season or who consumed fish

attributable to rivers and streams

The median consumption rate for All Anglers from

All Waters was 11 gday while the 75th percentile

for this group was 42 gday and the 95th percentile

was 21 gday Median consumption for Consuming

Anglers was 20 gday with a 75th percentile of 58

gday and a 95th percentile of 26 gday For flowing

waters only the median consumption rate for all

anglers consuming and not consuming was 0 gday

with a 75th percentile of 037 gday and a 95th

percentile of 44 gday For all River Anglers

including consumers and non consumers the

median consumption rate was 0 gday with a 75th

percentile of 081 gday and a 95th percentile of 57

gday For Consuming Anglers only the median

consumption rate was 099 gday with a 75th

percentile of 25 gday and a 95th percentile of 12

gday

DISCUSSION

The EPA has stated that whenever possible data on

local consumption patterns should be collected or

obtained from a current database EPA 1989b

This survey was undertaken in an effort to provide

information on the freshwater fish consumption

habits of Maine anglers The results of this study

provide the most accurate and only known

characterization of freshwater fish consumption

habits by Maines anglers

A significant finding of this survey is that many

anglers do not consume any freshwater fish Twenty

three percent of all anglers surveyed reported that

they consumed no freshwater fish caught in 1990

Fiftyfive percent of the river anglers surveyed

reported that they ate no freshwater fish during the

1990 season

In this statewide mail survey the median

consumption rate for all anglers and for river anglers

on flowing waters including non consumers was 0

gday while the median for consuming anglers on

flowing waters was 099 gday For all waterbody

types the median for all anglers was 11 gday and

the median for consuming anglers only was 20

gday

It is important to note that because the fish

consumption rates are positively skewed rather than

symmetrically distributed the arithmetic mean is not

the most appropriate descriptive measure of the

center of the distribution The median or 50th

percentile is a more physically relevant central

tendency measure for a skewed dataset as 50 percent

of consumption rate estimates lie above the median

and 50 percent fall below the median Thus the

median values provide the most representative

consumption rate estimate for each of the angler

populations

It is likely that these fish consumption rates may be

overestimated due to survey biases Chase and

1992 Environmental Conference 899

EPA001546
Harada 1984 have reported that participants

responding to selfreport surveys tend to over report

their actual participation in recreational activities

Similar results were reported by Soldat 1970 in his

survey of Columbia River anglers In a study done

for the US Fish and Wildlife Service Westat Inc

1989 reported that a oneyear recall period

produced substantial overestimates of fishing

statistics Westat Inc 1989 stated that factors that

can affect reporting include the length of the recall

period the frequency of the fishing trips interest in

or importance of the activity to the individual and

the perceived social desirability of the activity

Similarbiases have been reported in other studies of

recreational activities Ghosh 1978 Chase

Godbey 1983

The results of this survey indicate that the

consumption of freshwater fish by Maines anglers

is low The consumption rate estimates for the

median consumers in each of the angler groups were

well below the EPAs 1984 recommended per

capita estimate of 65 giday In fact the EPAs

estimate represents the 96th percentile of

consumption for all river anglers and the 92nd

percentile of consuming river anglers Results of

this study indicate that rates of consumption of

freshwater fish from Maines rivers are considerably

lower than those from Maines lakes and ponds or

from rivers in other regions of the country

900 TAPPI Proceedings

EPA001547
Table 1 Analysis of Fish Consumption Rates

All Watersa Rivers and Streams 1

All Consuming All River Consuming

Anglersc Anglersd Anglersc Anglers eAnglersd

N of Cases 1369 1053 1369 745 464

Median 50th percentilefg 11 20 0 028 099

66th percentile fg 26 40 0 085 18

75th percentile fg 42 58 037 14 25

Arithmetic Mean f50 64 12 23 37

Percentile at the Mean g 79 77 85 83 81

90th percentile fg 11 13 21 42 61

95th percentile fg 21 26 44 67 12

Percentile at 65 gday gh 83 77 97 95 92

a All Waters based on fish obtained from all lakes ponds streams and rivers in Maine from other household sources and from other

non household sources

b Rivers and Streams based on fish caught only from rivers and streams in Maine

c All Anglers includes survey respondents consumers and non consumers who fished during the 19891990 ice fishing or 1990 open

water seasons as well as those anglers who did not fish but reported consuming freshwater fish caught from Maine sources during those

seasons

d Consuming Anglers refers to only those anglers who consumed freshwater fish obtained from Maine sources during the 19891990 ice

fishing or 1990 open water fishing season

e River Anglers is a subset of All Anglers River Anglers includes survey respondents consumers and non consumers who

indicated that they fished on rivers or streams during the 1990 open water season

f Fish consumption rates are expressed in gpersonday and are the average consumption per day by freshwater fish consumers in the

household Fish consumption rates under All Waters are based on reported consumption from all Maine sources and estimated

consumption during 1990 after the survey was completed Rates summarized under Rivers and Streams are based on reported

consumption from rivers and streams estimated consumption during 1990 after the survey was completed and estimated consumption

from other household and non household sources attributable to rivers and streams

g Calculated by rank without any assumption of statistical distribution

h Fish consumption rate recommended by EPA 1984 for use in establishing ambient water quality standard

1992 Environmental Conference 901

EPA001548
REFERENCES

1 KJ Boyle ML Phillips and SD Reiling

Department of Agricultural and Resource

Economics Staff Paper Series in Resource

Economics Highlights from the Survey of Anglers

Holding a 1987 Maine Fishing License ARE 398

June 1989

2 DR Chase and M Harada Journal of Leisure

Research Response Error in Self Reported

Recreation Participation 15 4 322329 1984

3 DR Chase and GC Godbey Leisure Studies

Research note The Accuracy of SelfReported

Participation Rates Vol 2 231235 1983 Cited

in USFWS 1989

4 RS Cone Trans Am Fish Soc The Need

to Reconsider the Use of Condition Indices in

Fishery Science 118 510514 1989

5 ES Ebert Edible Portion of Smallmouth Bass

Landlocked Salmon and White Perch from Maine

Rivers Memorandum from ES Ebert to Project

file January 11 1991a

6 ES Ebert Analysis of Fish from the Penobscot

River Memorandum to the Project File March 22

199 lb

7 EPA Ambient Water Quality Criteria for 2378

tetrachlorodibenzopdioxin Office of Water

Regulations and Standards US Environmental

Protection Agency Washington DC

EPA440584007 1984

8 EPA Exposure Factors Handbook Office of

Health and Environmental Assessment US

Environmental Protection Agency Washington

DC EPA600889043 July 1989a

9 EPA Assessing Human Health Risks from

Chemically Contaminated Fish and Shellfish A

Guidance Manual US Environmental Protection

Agency Office of Marine and Estuarine Protection

Office of Water Regulations and Standards

Washington DC EPA503889002 September

1989b

10 DN Ghosh Optional Recall for Discrete

Events American Statistical Association 1978

Proceedings of the Section on Survey Research

Methods 615616 1978 Cited as Ghosh 1977 in

USFWS 1989

11 JF Honstead TM Beetle and JK Soldat A

Statistical Study of the Habits of Local Fishermen

and Its Application to Evaluation of Environmental

Dose A Report to the Environmental Protection

Agency by Battelle Pacific Northwest Laboratories

Richland WA 1971

12 HEB Humphrey Private Communication

1978 Cited in Rupp et al 1980

13 H Javitz Seafood Consumption Data Analysis

SRI International Final report prepared for Office

of Water Regulations and Standards US

Environmental Protection Agency Washington

DC EPA Contract 68013887 1980 Cited in

EPA 1989a

14 LA Nielsen and DL Johnson Fisheries

Techniques American Fisheries Society Bethesda

1983

15 AH Parsons SL Huntley ES Ebert ER

Algeo and RE Keenan Chemosphere Risk

Assessment for Dioxin in Columbia River Fish

231112 17091717 1991

16 RS Pierce DT Noviello and SH Rogers

Commencement Bay Seafood Consumption Report

Preliminary Report Tacoma WA Tacoma Pierce

County Health Department 1981

17 H Puffer Consumption Rates of Potentially

Hazardous Marine Fish Caught in the Metropolitan

Los Angeles Area EPA Grant R807 120010

1981

18 EM Rupp FL Miller and ICF Baes

Health Physics Some Results of Recent Surveys

Fish and Shellfish Consumption by Age and Region

of US Residents 39 165175 1980

902 TA PPProceedings

EPA001549
19 JK Soldat A Statistical Study of the Habits of

Fishermen Utilizing the Columbia River Below

Hanford Chapter 25 In Environmental

Surveillance in the Vicinity of Nuclear Facilities

Proceedings of a Symposium Sponsored by the

Health Physics Society January 2426 1968

William C Reinig ed Springfield IL Charles C

Thomas 1970 p 302308

20 SPSS SPSSPC+Tm Update for V31 SPSS

Data Entry IIrm Chicago IL 1989

21 Westat Inc Investigation of Possible

RecallReference Period Bias in National Surveys of

Fishing Hunting and Wildlife Associated

Recreation Final Report Contract no 1416009

87008 Prepared for the US Fish and Wildlife

Service by Westat Inc Rockville MD December

1989

1992 Environmental Conference 903

EPA001550
Session 31 Poster Session

The following papers Session 31 have been reviewed by the Technical

Program Committee of the TAPPI Environmental Division and approved for

publication based on two criteria 1 the ideas appear to be new and 2 the

papers present technical information rather than a commercial

904 TAPPI Proceedings

EPA001551