A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats.
The lengths of otoliths and other skeletal structures recovered from the seats of pinnipeds, such as Steller sea lions (Eumetopias jubatus), correlate with body size and can be used to estimate the length of prey consumed. Unfortunately, otoliths are often found in too few scats or are too digested...
Main Authors: | , , , , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2004
|
Subjects: | |
Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/a-method-to-improve-size-estimates-of-walleye-pollock-theragra-chalcogramma-and-atka-mackerel-pleurogrammus-monopterygius-consumed-by-pinnipeds-digestion-correction-factors-applied-to-bones-and-otoliths-recovered-in-scats(1ec095c2-7de1-48aa-96c2-9d6dc800f022).html http://www.scopus.com/inward/record.url?scp=3543128913&partnerID=8YFLogxK http://fishbull.noaa.gov/1023/tollit1.pdf |
id |
ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/1ec095c2-7de1-48aa-96c2-9d6dc800f022 |
---|---|
record_format |
openpolar |
spelling |
ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/1ec095c2-7de1-48aa-96c2-9d6dc800f022 2023-05-15T15:44:00+02:00 A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. Tollit, D.J. Heaslip, Susan Gale Zeppelin, T.K. Joy, R. Call, K.A. Trites, A.W. 2004-07 https://risweb.st-andrews.ac.uk/portal/en/researchoutput/a-method-to-improve-size-estimates-of-walleye-pollock-theragra-chalcogramma-and-atka-mackerel-pleurogrammus-monopterygius-consumed-by-pinnipeds-digestion-correction-factors-applied-to-bones-and-otoliths-recovered-in-scats(1ec095c2-7de1-48aa-96c2-9d6dc800f022).html http://www.scopus.com/inward/record.url?scp=3543128913&partnerID=8YFLogxK http://fishbull.noaa.gov/1023/tollit1.pdf eng eng info:eu-repo/semantics/restrictedAccess Tollit , D J , Heaslip , S G , Zeppelin , T K , Joy , R , Call , K A & Trites , A W 2004 , ' A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. ' , Fishery Bulletin , vol. 102 , no. 3 , pp. 498-508 . SEALS CALLORHINUS-URSINUS EUMETOPIAS-JUBATUS BERING SEA SKELETAL STRUCTURES DIET COMPOSITION FECAL SAMPLES PREY ISLAND CONSUMPTION SCOTLAND article 2004 ftunstandrewcris 2021-12-26T14:13:59Z The lengths of otoliths and other skeletal structures recovered from the seats of pinnipeds, such as Steller sea lions (Eumetopias jubatus), correlate with body size and can be used to estimate the length of prey consumed. Unfortunately, otoliths are often found in too few scats or are too digested to usefully estimate prey size. Alternative diagnostic bones are frequently recovered, but few bone-size to prey-size correlations exist and bones are also reduced in size by various degrees owing to digestion. To prevent underestimates in prey sizes consumed techniques are required to account for the degree of digestion of alternative bones prior to estimating prey size. We developed a method (using defined criteria and photo-reference material) to assign the degree of digestion for key cranial structures of two prey species: walleye pollock (Theragra chalcogramma) and Atka mackerel (Pleurogrammus monopterygius). The method grades each structure into one of three condition categories; good, fair or poor. We also conducted feeding trials with captive Steller sea lions, feeding both fish species to determine the extent of erosion of each structure and to derive condition-specific digestion correction factors to reconstruct the original sizes of the structures consumed. In general, larger structures were relatively more digested than smaller ones. Mean size reduction varied between different types of structures (3.3-26.3%), but was not influenced by the size of the prey consumed. Results from the observations and experiments were combined to be able to reconstruct the size of prey consumed by sea lions and other pinnipeds. The proposed method has four steps: 1) measure the recovered structures and grade the extent of digestion by using defined criteria and photo-reference collection; 2) exclude structures graded in poor condition; 3) multiply measurements of structures in good and fair condition by their appropriate digestion correction factors to derive their original size; and 4) calculate the size of prey from ... Article in Journal/Newspaper Bering Sea Theragra chalcogramma Callorhinus ursinus University of St Andrews: Research Portal Atka ENVELOPE(151.789,151.789,60.835,60.835) Bering Sea |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
SEALS CALLORHINUS-URSINUS EUMETOPIAS-JUBATUS BERING SEA SKELETAL STRUCTURES DIET COMPOSITION FECAL SAMPLES PREY ISLAND CONSUMPTION SCOTLAND |
spellingShingle |
SEALS CALLORHINUS-URSINUS EUMETOPIAS-JUBATUS BERING SEA SKELETAL STRUCTURES DIET COMPOSITION FECAL SAMPLES PREY ISLAND CONSUMPTION SCOTLAND Tollit, D.J. Heaslip, Susan Gale Zeppelin, T.K. Joy, R. Call, K.A. Trites, A.W. A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. |
topic_facet |
SEALS CALLORHINUS-URSINUS EUMETOPIAS-JUBATUS BERING SEA SKELETAL STRUCTURES DIET COMPOSITION FECAL SAMPLES PREY ISLAND CONSUMPTION SCOTLAND |
description |
The lengths of otoliths and other skeletal structures recovered from the seats of pinnipeds, such as Steller sea lions (Eumetopias jubatus), correlate with body size and can be used to estimate the length of prey consumed. Unfortunately, otoliths are often found in too few scats or are too digested to usefully estimate prey size. Alternative diagnostic bones are frequently recovered, but few bone-size to prey-size correlations exist and bones are also reduced in size by various degrees owing to digestion. To prevent underestimates in prey sizes consumed techniques are required to account for the degree of digestion of alternative bones prior to estimating prey size. We developed a method (using defined criteria and photo-reference material) to assign the degree of digestion for key cranial structures of two prey species: walleye pollock (Theragra chalcogramma) and Atka mackerel (Pleurogrammus monopterygius). The method grades each structure into one of three condition categories; good, fair or poor. We also conducted feeding trials with captive Steller sea lions, feeding both fish species to determine the extent of erosion of each structure and to derive condition-specific digestion correction factors to reconstruct the original sizes of the structures consumed. In general, larger structures were relatively more digested than smaller ones. Mean size reduction varied between different types of structures (3.3-26.3%), but was not influenced by the size of the prey consumed. Results from the observations and experiments were combined to be able to reconstruct the size of prey consumed by sea lions and other pinnipeds. The proposed method has four steps: 1) measure the recovered structures and grade the extent of digestion by using defined criteria and photo-reference collection; 2) exclude structures graded in poor condition; 3) multiply measurements of structures in good and fair condition by their appropriate digestion correction factors to derive their original size; and 4) calculate the size of prey from ... |
format |
Article in Journal/Newspaper |
author |
Tollit, D.J. Heaslip, Susan Gale Zeppelin, T.K. Joy, R. Call, K.A. Trites, A.W. |
author_facet |
Tollit, D.J. Heaslip, Susan Gale Zeppelin, T.K. Joy, R. Call, K.A. Trites, A.W. |
author_sort |
Tollit, D.J. |
title |
A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. |
title_short |
A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. |
title_full |
A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. |
title_fullStr |
A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. |
title_full_unstemmed |
A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. |
title_sort |
method to improve size estimates of walleye pollock ( theragra chalcogramma ) and atka mackerel ( pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. |
publishDate |
2004 |
url |
https://risweb.st-andrews.ac.uk/portal/en/researchoutput/a-method-to-improve-size-estimates-of-walleye-pollock-theragra-chalcogramma-and-atka-mackerel-pleurogrammus-monopterygius-consumed-by-pinnipeds-digestion-correction-factors-applied-to-bones-and-otoliths-recovered-in-scats(1ec095c2-7de1-48aa-96c2-9d6dc800f022).html http://www.scopus.com/inward/record.url?scp=3543128913&partnerID=8YFLogxK http://fishbull.noaa.gov/1023/tollit1.pdf |
long_lat |
ENVELOPE(151.789,151.789,60.835,60.835) |
geographic |
Atka Bering Sea |
geographic_facet |
Atka Bering Sea |
genre |
Bering Sea Theragra chalcogramma Callorhinus ursinus |
genre_facet |
Bering Sea Theragra chalcogramma Callorhinus ursinus |
op_source |
Tollit , D J , Heaslip , S G , Zeppelin , T K , Joy , R , Call , K A & Trites , A W 2004 , ' A method to improve size estimates of walleye pollock ( Theragra chalcogramma ) and Atka mackerel ( Pleurogrammus monopterygius ) consumed by pinnipeds: digestion correction factors applied to bones and otoliths recovered in scats. ' , Fishery Bulletin , vol. 102 , no. 3 , pp. 498-508 . |
op_rights |
info:eu-repo/semantics/restrictedAccess |
_version_ |
1766378227462307840 |