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.

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.

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.

Effect of Changes in Recruitment Levels on Multispecies Long-term Predictions

1993 ◽  
Vol 50 (11) ◽  
pp. 2315-2322 ◽  
Author(s):  
Henrik Gislason
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Relative Increase ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Fish Stocks ◽  
The North ◽  
Predation Mortality ◽  
Spawning Stock ◽  
Relative Change

A multispecies model (MSFOR) is used to predict the relative change in equilibrium yield and spawning stock biomass (SSB) of commercially important fish stocks in the North Sea resulting from a reduction in the fishing mortality generated by the roundfish fishery. Because predation mortality is a function of the abundance of prey and predators the results will depend on recruitment. Assuming recruitment to be independent of stock sizes the effect of changes in recruitment is studied by repeating the predictions at all possible combinations of ±50% changes in predator and prey recruitment levels. All of the predictions result in a relative increase in the SSB of Atlantic cod (Gadus morhua) and saithe (Pollachius virens) and in a relative decrease in the SSB of Atlantic herring (Clupea harengus) and Norway pout (Trisopterus esmarkii). In these cases the sign of the relative change is robust to recruitment changes. However, for haddock (Melanogrammus aeglefinus), sprat (Sprattus sprattus), and sandeel (Ammodytes marinus) the relative change in SSB is found to be either positive or negative depending on the level of recruitment. The predictions for haddock are highly sensitive to changes in the level of saithe recruitment.

Pelagic fish outburst or suprabenthic habitat occupation: legacy of the Atlantic cod (Gadus morhua) collapse in eastern Canada

2009 ◽  
Vol 66 (12) ◽  
pp. 2256-2262 ◽  
Author(s):  
Ian H. McQuinn
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Pelagic Fish ◽  
Clupea Harengus ◽  
Bottom Trawl ◽  
Eastern Canada ◽  
The Past ◽  
Research Survey ◽  
Fisheries Statistics ◽  
Fish Abundances

The use of bottom-trawl research survey data to estimate population trends for small pelagic fishes, despite the extremely low selectivity of this gear for these species, has created the impression of a pelagic fish outburst along eastern Canada in the 1990s as a top-down response resulting from the demise of the Atlantic cod ( Gadus morhua ) and other groundfish. Using Atlantic herring ( Clupea harengus ) population assessments, fisheries statistics, and an acoustic database, as well as grey seal (Halichoerus grypus) diet studies, I demonstrate that contrary to a pelagic outburst, pelagic catches in research bottom trawls increased in several eastern Canadian ecosystems as these species increasingly occupied the suprabenthic habitat vacated by their diminishing groundfish predators. Although several herring populations were actually decreasing in abundance, bottom-trawl indices (BTIs) were dramatically increasing as their availability to research bottom-trawl surveys increased. Studies using BTIs have systematically underestimated pelagic fish abundances before the cod decline and therefore have dramatically overestimated their importance since, seriously biasing our view of the past and present state of many Canadian east coast ecosystems.

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.

scholarly journals The sampling volume of trawl and acoustics: estimating availability probabilities from observations of tracked individual fish

2009 ◽  
Vol 66 (3) ◽  
pp. 425-437 ◽  
Author(s):  
Nils Olav Handegard ◽  
Dag Tjøstheim
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Initial Position ◽  
Bottom Trawl ◽  
Melanogrammus Aeglefinus ◽  
Individual Fish ◽  
Sampling Volume ◽  
Swimming Trajectories ◽  
Echo Sounder

The effective sampling volume of trawl and acoustics is an important parameter in fish abundance estimation surveys. This paper presents a method to compute the probability of a fish being available to the bottom trawl and the probability of it being seen on the echo sounder, given its initial position relative to the vessel path. These probabilities are then related to the calculation of the effective observational volume for trawl and acoustics, the two main tools of measuring abundance of Atlantic cod ( Gadus morhua ) and haddock ( Melanogrammus aeglefinus ). As an example, the computation is carried out for a typical vertical distribution in the Barents Sea. Our model is based on an Ornstein–Uhlenbeck model for the fish swimming trajectories, and its parameters are estimated using observations of swimming trajectories for individual fish, recorded by a split-beam echo sounder. The model itself constitutes a general method to translate observations on behaviour of individual fish to probability maps. The results indicate a typical fishing height of 20 m for the bottom trawl, but it is also shown that there is a relatively low probability of catching by the trawl what you see on the echo sounder, even for fish positioned directly in the trawl path. This is because of strong lateral movements of the fish.

Consideration of the Stable Age Distribution Assumption in "Analytical" Yield Models

1983 ◽  
Vol 40 (1) ◽  
pp. 95-101 ◽  
Author(s):  
M. Sinclair ◽  
R. O'Boyle ◽  
T. D. Iles
Keyword(s):  
Analytical Model ◽  
Growth Rates ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Age Distribution ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Yield Model ◽  
Stable Age Distribution ◽  
Recruitment Variability

The implications on the "analytical" yield model of deviations from the stable age distribution were investigated for stocks of five species with a range of life history characteristics, these being Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), pollock (Pollachius virens), Atlantic herring (Clupea harengus harengus), and Atlantic mackerel (Scomber scrombus). Recruitment variability for the stocks considered ranged from 21% for pollock to 104% for haddock. The comparison of the growth rates at age for the five species showed the expected continuum in relative growth rates from cod to mackerel. With the population in a stable age distribution without fishing there is also a continuum from cod to mackerel in the manner in which age-specific production decreases through the life span. It is thus to be expected that deviations from the stable age distributions for mackerel would have a much greater impact on population production than would a similar deviation for cod. Also, species whose growth rates decrease more rapidly with age tend to have a higher recruitment variability. To demonstrate the implications of deviations from the stable age distribution on the accuracy of model output, MSY yields (that would have been generated given historical estimates of population numbers-at-age) were compared to estimates of annual population production. Cod and pollock production deviate relatively little from the "analytical" model predictions. In contrast, annual production for haddock, herring, and mackerel deviate markedly from MSY yields as the age composition deviates in each direction from the stable age distribution. The analysis suggests that for some species the "analytical" model may contribute to growth overfishing.Key words: "analytical" yield models, stable age distribution, growth overfishing

Parasites as biological tags in marine fisheries research: European Atlantic waters

Parasitology ◽  
2014 ◽  
Vol 142 (1) ◽  
pp. 54-67 ◽  
Author(s):  
K. MACKENZIE ◽  
W. HEMMINGSEN
Keyword(s):  
Marine Mammals ◽  
Gadus Morhua ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Ecological Group ◽  
The North ◽  
Recent Developments ◽  
Host Parasite ◽  
Mediterranean And Black Seas ◽  
Biological Tags

SUMMARYStudies of the use of parasites as biological tags for stock identification and to follow migrations of marine fish, mammals and invertebrates in European Atlantic waters are critically reviewed and evaluated. The region covered includes the North, Baltic, Barents and White Seas plus Icelandic waters, but excludes the Mediterranean and Black Seas. Each fish species or ecological group of species is treated separately. More parasite tag studies have been carried out on Atlantic herring Clupea harengus than on any other species, while cod Gadus morhua have also been the subject of many studies. Other species that have been the subjects of more than one study are: blue whiting Micromesistius poutassou, whiting Merlangius merlangus, haddock Melanogrammus aeglefinus, Norway pout Trisopterus esmarkii, horse mackerel Trachurus trachurus and mackerel Scomber scombrus. Other species are dealt with under the general headings redfishes, flatfish, tunas, anadromous fish, elasmobranchs, marine mammals and invertebrates. A final section highlights how parasites can be, and have been, misused as biological tags, and how this can be avoided. It also reviews recent developments in methodology and parasite genetics, considers the potential effects of climate change on the distributions of both hosts and parasites, and suggests host-parasite systems that should reward further research.

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