Predation risk on larval gadids by pelagic fish in the Georges Bank ecosystem. I. Spatial overlap associated with hydrographic features

2000 ◽  
Vol 57 (12) ◽  
pp. 2455-2469 ◽  
Author(s):  
Lance P Garrison ◽  
William Michaels ◽  
Jason S Link ◽  
Michael J Fogarty
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Clupea Harengus ◽  
Planktivorous Fish ◽  
Melanogrammus Aeglefinus ◽  
Spatial Distributions ◽  
Georges Bank ◽  
Spatial Overlap ◽  
Atlantic Mackerel ◽  
Fish Predators

We investigated the relationship between hydrographic variables on Georges Bank and the spatial distribution of larval Atlantic cod (Gadus morhua), larval haddock (Melanogrammus aeglefinus), and two planktivorous fish, Atlantic herring (Clupea harengus) and Atlantic mackerel (Scomber scombrus). We conducted cruises during April-May of 1990, 1994, and 1995 to document spatial distributions and employed logistic regression and a spatial-overlap index to assess relationships between hydrographic variables, spatial distributions and spatial overlap between gadid larvae and planktivorous fish. Cod larvae were more abundant in shallow well-mixed areas, while both haddock larvae and herring were more abundant in stratified areas. Atlantic mackerel occurred in deeper water and had little spatial overlap with the other species. In 1995, the presence of Scotian Shelf water and an intrusion of continental slope water altered temperature and salinity distributions and increased spatial overlap between cod larvae and herring. The stratified areas offer a higher concentration of prey for larval haddock, however there is increased exposure to planktivorous fish predators, creating a potential trade-off between predation and starvation. Due to the high abundance of planktivorous fish and high spatial and temporal overlap, predation is likely an important factor influencing survival of gadid larvae on Georges Bank.

Recent Growth, Biochemical Composition and Prey Field of Larval Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) on Georges Bank

1987 ◽  
Vol 44 (1) ◽  
pp. 14-25 ◽  
Author(s):  
L. J. Buckley ◽  
R. G. Lough
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Dry Weight ◽  
Melanogrammus Aeglefinus ◽  
Good Growth ◽  
Georges Bank ◽  
Larval Population ◽  
Prey Biomass ◽  
Recent Growth ◽  
Haddock Melanogrammus Aeglefinus

A transect across southern Georges Bank in May 1983 showed higher levels of available prey for haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) larvae at two stratified sites than at a well-mixed site. At the stratified sites, prey biomass was high (30–300 μg dry wt∙L−1) near the surface above the thermocline; values were lower and more uniform with depth (10–30 μg dry wt∙L−1) at the well-mixed site. Larval population centers generally coincided with prey biomass vertically. Recent growth in dry weight of haddock larvae as estimated by RNA–DNA ratio analysis was higher at the stratified sites (8–13%∙d−1) than at the well-mixed site (7%∙d−1). Larvae appeared to be in excellent condition at the stratified sites, but up to 50% of haddock larvae from the well-mixed site had RNA–DNA ratios in the range observed for starved larvae in the laboratory. Cod collected at the same site were in better condition and growing faster than haddock. The data support the hypotheses that (1) stratified conditions in the spring favor good growth and survival of haddock larvae and (2) cod larvae are better adapted to grow and survive in well-mixed waters at lower levels of available food than haddock larvae.

Fish Catches and Long-Term Tidal Cycles in Northwest Atlantic Fisheries: A Nonlinear Regression Approach

1987 ◽  
Vol 44 (11) ◽  
pp. 1890-1897 ◽  
Author(s):  
Paul Cabilio ◽  
David L. DeWolfe ◽  
Graham R. Daborn
Keyword(s):  
New England ◽  
Nonlinear Regression ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Significant Negative Correlation ◽  
Clupea Harengus ◽  
Atlantic Menhaden ◽  
Melanogrammus Aeglefinus ◽  
Grand Banks

Selected long-term fisheries catch data from the New England – Fundy area and the Grand Banks were examined for concordance between changes in fish catches and the 18.6-yr nodal cycle of the tides using a nonlinear regression model. Significant positive correlations were found for Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), alewife (Alosa pseudoharengus), Atlantic herring (Clupea harengus harengus), and scallop (Placopecten magellanicus), with lag times that are biologically appropriate for the time from hatching to recruitment into the fishery. A significant negative correlation with the nodal cycle was evident for Atlantic menhaden (Brevoortia tyrannus), for which this area constitutes the most northerly part of its range. Cod catches on the Grand Banks showed no correlation with the nodal cycle. It is suggested that the correlations between the nodal cycle and the changes in fish catches are caused by correlated changes either in sea surface temperature or in productivity resulting from changes in the degree of vertical mixing.

scholarly journals Fecundity estimation of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) of Georges Bank: Application of the autodiametric method

2009 ◽  
Vol 99 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Alexandre Alonso-Fernández ◽  
Ann Carole Vallejo ◽  
Fran Saborido-Rey ◽  
Hilario Murua ◽  
Edward A. Trippel
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Haddock Melanogrammus Aeglefinus

Larval Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) growth on Georges Bank: a model with temperature, prey size, and turbulence forcing

1999 ◽  
Vol 56 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Andrew W Leising ◽  
Peter JS Franks
Keyword(s):  
Prey Density ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Variable Temperature ◽  
Larval Growth ◽  
Temperature Cycle ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Temperature Cycles ◽  
Haddock Melanogrammus Aeglefinus

Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) on Georges Bank are subjected to a high degree of variability in temperature, turbulence, and prey densities, depending on when they are spawned and where they are advected. We have developed an individual-based model that includes the effect of varying prey density, turbulence, and temperature. Temperature effects were included by using a Q10-type adjustment to the standard metabolic rate as well as a second temperature-dependent term added to the overall ingestion ability of our model fish, a function of the swimming speed, capture efficiency, and "liveliness" of a fish. Three cases were analyzed: (i) constant food and temperature conditions, (ii) variable temperature cycles, and (iii) variable temperature cycles plus turbulence. We found that prey density, turbulence, and temperature ranges typical of the peak spawning season are variable enough to be limiting to larval growth. The timing and location of spawning are crucial to the survival of the larvae. Increasing the average temperature cycle by 1°C, as might occur due to climatological change or interannual variability, increased growth for larvae that were not growing well previously. The increased temperature failed to increase larval growth in areas where larvae were already growing at rates close to their maximum.

Estimating the biomass of a mixed species complex using hydroacoustics and catch data from the Bay of Fundy and Scotian Shelf summer ecosystem survey

2020 ◽  
Vol 77 (7) ◽  
pp. 1101-1116
Author(s):  
Allan J. Debertin
Keyword(s):  
Species Composition ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Clupea Harengus ◽  
Bottom Trawl ◽  
Melanogrammus Aeglefinus ◽  
Acoustic Data ◽  
Catch Data ◽  
Scatter Coefficient ◽  
Management Advice

An acoustic-based index of biomass was developed due to concerns that the existing bottom-trawl index for western component pollock (Pollachius virens) was inaccurate and imprecise. Acoustic data were recorded during annual summer ecosystem surveys. Pollock and other common groundfish could not be readily identified from echo-traces within echograms. Survey catch data were analyzed concurrently with acoustic data to estimate biomass from echo-integrals contributed by the six most commonly caught fish species: pollock, Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), redfish (Sebastes fasciatus), Atlantic herring (Clupea harengus), and spiny dogfish (Squalus acanthias). A cluster analyses that used a Bayesian conditional probability classified homogeneous regions based on species composition. Species composition, nautical area scatter coefficient, and backscattering cross-section of fishes for regions were used to calculate the biomass of fishes. Acoustic indices were considered as appropriate as bottom-trawl indices for fisheries management advice because the bias and variance were similar between the indices when analyzed using repeated K-fold cross-validation.

Production Responses for Multi-species Fisheries

1981 ◽  
Vol 38 (11) ◽  
pp. 1393-1404 ◽  
Author(s):  
R. J. Agnello ◽  
L. G. Anderson
Keyword(s):  
New England ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Clupea Harengus ◽  
Categorical Variables ◽  
Melanogrammus Aeglefinus ◽  
Target Species ◽  
Northwest Atlantic ◽  
Fisheries Economics ◽  
Log Linear

Production equations are estimated for five major species of fish harvested in the Northwest Atlantic including Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), flounder (Pleuronectiformes), redfish (Sebastes marinus), and herring (Clupea harengus) using data collected by the International Commission for the Northeast Atlantic Fisheries from 1960 to 1974. A log-linear regression specification is used in which the relationship between catch of a vessel and several factors including days fished and vessel characteristics is estimated simultaneously. Vessel characteristics are represented as (0, 1) categorical variables, and include a variable indicating the target species designated by the caption. Various settings for the target species variables allow the estimated equation to represent either a by-catch or target catch equation. The production parameters estimated by the regressions are used to analyze the effects of current quotas set by the New England Fisheries Management Council. For some fleets we find a likelihood of idle capacity given the current quotas.Key words: fisheries economics, multi-species harvesting, Northwest Atlantic fisheries

Species-specific residence times in the aft part of a pelagic survey trawl: implications for inference of pre-capture spatial distribution using the Deep Vision system

2018 ◽  
Vol 75 (4) ◽  
pp. 1393-1404 ◽  
Author(s):  
Melanie J Underwood ◽  
Shale Rosen ◽  
Arill Engås ◽  
Terje Jørgensen ◽  
Anders Fernö
Keyword(s):  
Spatial Distribution ◽  
Residence Time ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Vision System ◽  
Ground Truth ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Camera System ◽  
Species Specific

Abstract In-trawl camera systems promise to improve the resolution of trawl sampling used to ground-truth the interpretation of acoustic survey data. In this study, the residence time of fish in front of the Deep Vision camera system, used to identify, measure and count fish inside the trawl, was analysed to determine the reliability of spatial distribution recorded by the system. Although Atlantic herring (Clupea harengus), haddock (Melanogrammus aeglefinus), and most Atlantic cod (Gadus morhua) moved quickly back through the aft part of the pelagic trawl, saithe (Pollachius virens) spent up to 4 min in front of the system. The residence time increased for saithe and cod when other individuals were present, and cod swimming in the low water flow close to the trawl netting spent longer there than cod at the centre of the trawl. Surprisingly, residence time was not related to the size of the fish, which may be explained by the collective behaviour of shoaling fish. Our findings suggest that while in-trawl images can be used to identify, measure and count most species, when sampling fast-swimming species such as saithe the position inferred from when they were imaged may not reflect the actual spatial distribution prior to capture.

Predicting Recruitment Variation from Year Class Specific Vertebral Counts: An Analysis of the Potential and a Plan for Verification

1991 ◽  
Vol 48 (8) ◽  
pp. 1350-1357 ◽  
Author(s):  
Kenneth T. Frank
Keyword(s):  
Environmental Factors ◽  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Negative Relationship ◽  
Early Life History ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Southern Limit ◽  
Stock Discrimination

Recruitment prediction has been an elusive and seemingly unobtainable goal with no entirely satisfactory general approach yet available. I propose the use of meristic variation, traditionally applied to problems associated with stock discrimination studies, as a new method to predict recruitment variation. The approach is evaluated using literature data on year class strength (YCS) and year class specific average vertebral counts (VS), two apparently interrelated variables that are affected by environmental factors operating during the early life history. Three marine stocks at the southern limit of their species geographic range (Georges Bank haddock (Melanogrammus aeglefinus), North Sea Atlantic cod (Gadus morhua), and North Sea Atlantic herring (Clupea harengus hargenus)) and one stock at its northern limit (Pacific herring (Clupea harengus pallasi)) generally conformed to the prediction of a positive relationship between YCS and VS for southern stocks and a negative relationship for northern stocks. Exceptions to these patterns were found among stocks showing low temporal variability in recruitment or for stocks whose year class formation is not linked to environmental factors that establish the vertebral count of a year class. The approach adopted is consistent with the growing initiative of focusing on characteristics of the survivors of a population to provide insight into recruitment mechanisms.

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