Assimilation efficiency of adult Kittiwakes and Br�nnich's Guillemots fed Capelin and Arctic Cod

Polar Biology ◽  
1994 ◽  
Vol 14 (4) ◽  
Author(s):  
Bente Brekke ◽  
GeirWing Gabrielsen
Keyword(s):  
Assimilation Efficiency ◽  
Arctic Cod

Bioenergetics of Arctic cod (Boreogadus saida) at low temperatures

1997 ◽  
Vol 54 (8) ◽  
pp. 1772-1784 ◽  
Author(s):  
H Hop ◽  
W M Tonn ◽  
H E Welch
Keyword(s):  
Energy Budget ◽  
Growth Rates ◽  
Slow Growth ◽  
Energy Content ◽  
Assimilation Efficiency ◽  
High Energy ◽  
The Arctic ◽  
Small Fish ◽  
Boreogadus Saida ◽  
Arctic Cod

The Arctic cod (Boreogadus saida), a key component of the marine food web of Canadian high Arctic waters, occurs at temperatures close to or below zero. We established a complete energy budget for this Arctic fish, based on laboratory measurements of consumption (C), growth (G), respiration (R), egestion (F), and excretion (U) at about 0°C. An average (N = 3) energy budget for individual juvenile Arctic cod fed live Arctic zooplankton was 100C = 50G + 24R + 9SDA + 3F + 6U + 8Z, where SDA is specific dynamic action (derived from previously published studies) and Z included activity and unaccounted energy. Eight determinations of total energy budgets for fish fed to satiation accounted for 72-104% of the energy consumed. Maximum daily rations and growth rates were dependent on fish size and the energy content of prey. Although maximum daily rations were similar for small fish fed different prey, diets of Calanus copepods (high energy content) resulted in faster growth rates than diets of Themisto amphipods or capelin (Mallotus villosus) fillets. Both consumption and respiration rates were low at temperatures close to 0°C. The net result was slow growth rates, although the assimilation efficiency was about 80%. Because of slow growth of individuals, the relatively high annual production of Arctic cod mainly reflects their large standing biomass.

Variation in assimilation efficiency and digestive efficiency of captive harp seals (Phoca groenlandica) on different diets

1997 ◽  
Vol 75 (8) ◽  
pp. 1285-1291 ◽  
Author(s):  
John W. Lawson ◽  
Edward H. Miller ◽  
Elizabeth Noseworthy
Keyword(s):  
Atlantic Cod ◽  
Relative Concentration ◽  
Assimilation Efficiency ◽  
Clupea Harengus ◽  
Meal Size ◽  
Food Type ◽  
Digestive Efficiency ◽  
Greenland Halibut ◽  
Arctic Cod ◽  
Phoca Groenlandica

Digestive efficiency (DE) is influenced by many factors including food type or quality. Assimilation efficiency (AE) and DE of 12 captive harp seals (Phoca groenlandica) were estimated for five prey types in large outdoor seawater tanks. In trials of > 9 days' duration, the seals were fed Atlantic cod (Gadus morhua), Arctic cod (Boreogadus saida), Greenland halibut (Reinhardtius hippoglossoides), Atlantic herring (Clupea harengus), and capelin (Mallotus villosus). Fish were marked with inert tracers so that faecal samples could be matched to individual animals. AE (digestibility of dry matter) was estimated from the relative concentration of Mn2+ in food and faeces. DE (digestible energy) was estimated from the relative concentrations of both Mn2+ and energy in food and faeces. AE and DE values were high, but varied among the fish species (DE: Atlantic cod 93.5%; Arctic cod 93.5%; halibut 94.7%; capelin 95.7%; herring 96.6%). Both estimates of digestive efficiency were positively correlated with prey energy density. For most prey, AE and DE were not correlated with meal size, number of prey in a meal, size of prey, or seal body mass. However, digestive efficiency was greater in seals fed smaller Atlantic cod, or meals of greater mass. Quantifying estimates of digestive efficiency is important for formulating energy-based population consumption models, and so should be improved. It is recommended that more pinniped species be studied in captivity, that experiments last longer, and that the number of individuals studied be increased so that individual differences can be investigated.

scholarly journals On estimating the age composition of the commercial catch of Northeast Arctic cod from a sample of clusters

2003 ◽  
Vol 60 (2) ◽  
pp. 297-303 ◽  
Author(s):  
Aanes Sondre ◽  
Michael Pennington
Keyword(s):  
Age Structure ◽  
Age Distribution ◽  
Significant Loss ◽  
Effective Sample Size ◽  
Commercial Fishing ◽  
Total Catch ◽  
Intracluster Correlation ◽  
Age Composition ◽  
Commercial Catch ◽  
Arctic Cod

Abstract Assessment of Northeast Arctic cod is based on estimates of the commercial catch in numbers at age. The age structure of the catch is estimated by sampling fish from commercial fishing trips. Although it is commonly assumed that a sample of individuals is a random sample from the population, fish sampled from the same trip (i.e. from a “cluster” of fish) tend to be more similar in age than those in the total catch. For Northeast Arctic cod, the intracluster correlation for age is positive, and therefore the effective sample size is much smaller than the number of fish aged. Given the number of fish aged, the precision of the estimated age distribution is rather low, and the number of fish aged from each trip could be reduced from approximately 85 to 20 without a significant loss in precision.

Accuracy and precision in stock separation of north-east Arctic and Norwegian coastal cod by otoliths - comparing readings, image analyses and a genetic method

2005 ◽  
Vol 56 (5) ◽  
pp. 753 ◽  
Author(s):  
Erik Berg ◽  
Tuula H. Sarvas ◽  
Alf Harbitz ◽  
Svein Erik Fevolden ◽  
Arnt Børre Salberg
Keyword(s):  
Visual Inspection ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Complete Separation ◽  
Arctic Cod ◽  
Genetic Method ◽  
North East ◽  
Accuracy And Precision ◽  
Growth Zones ◽  
The Difference

The distinction between north-east Arctic cod and Norwegian coastal cod, two major groups of Atlantic cod (Gadus morhua L.), has for many years been based on different distance and shape similarities between the two first translucent growth zones in the otoliths, subjectively decided by visual inspection in a binocular. To analyse the certainty of this technique, four independent readers have classified 263 cod otoliths in total from five different geographical areas. For three of the readers, between 82% and 89% of the classification results coincided with independent results based on genetic analyses. Further, 38 cod otoliths, where the readers were certain of the classification (21 north-east Arctic cod and 17 coastal cod) were classified by several image analysis methods. A complete separation was obtained by using the ratio of the circumferences of the two zones, providing a typical ratio of approximately 2 for coastal and 1.5 for north-east Arctic cod. The otolith method for separating the two types of cod has been considered adequately accurate in assessing the two stocks of cod. However, the method is sensitive to subjective interpretation, and action needs to be taken to minimise the difference in interpretation among otolith readers.

Significance of Organic Detritus in the Diet of Larval Lampreys in the Great Lakes Basin

1994 ◽  
Vol 51 (11) ◽  
pp. 2380-2387 ◽  
Author(s):  
Trent M. Sutton ◽  
Stephen H. Bowen
Keyword(s):  
Great Lakes ◽  
Feeding Rate ◽  
Assimilation Efficiency ◽  
Dry Mass ◽  
Great Lakes Basin ◽  
Organic Detritus ◽  
Upper Peninsula ◽  
Sea Lampreys ◽  
Gut Fullness ◽  
Upper Peninsula Of Michigan

Larval sea lamprey (Petromyzon marinus) and northern brook lamprey (Ichthyomyzon fossor) were collected monthly from three streams in the Upper Peninsula of Michigan from May 1992 through May 1993 and larval sea lampreys were collected during summer months from sites throughout the Great Lakes basin. Organic detritus made up most of the diet ash-free-dry-mass (AFDM) throughout the year, averaging 97.79%, with algae (2.12%) and bacteria (0.09%) making up the remainder of the diet AFDM. Assimilation efficiency for AFDM averaged 72% during warmer months and 53% during cooler months (annual mean = 61%). Gut fullness (amount of AFDM in the anterior one-tenth of the intestine) was low (mean = 0.10 mg diet AFDM∙g−1 ammocoete). There were no significant differences in these measures between ammocoetes collected from the Upper Peninsula and those collected throughout the Great Lakes basin. From a laboratory-determined relationship between gut fullness and feeding rate, feeding rate in the field was estimated to be extremely slow, ranging from 4.2 to 5.5 mg diet AFDM∙g−1 ammocoete∙d−1. These observations indicate that larval lampreys efficiently utilize a diet of organic detritus during warmer months when stream temperatures and food quality are more favorable for feeding, digestion, and growth.

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