Microsatellite evaluation of haddock (Melanogrammus aeglefinus) stocks in the northwest Atlantic Ocean

2001 ◽  
Vol 58 (5) ◽  
pp. 982-990 ◽  
Author(s):  
Christopher Lage ◽  
Maureen Purcell ◽  
Michael Fogarty ◽  
Irv Kornfield
Keyword(s):  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Effective Number ◽  
Scotian Shelf ◽  
Genetic Structuring ◽  
Northwest Atlantic ◽  
Spawning Aggregations ◽  
The Impact ◽  
Significant Genetic Divergence ◽  
Haddock Melanogrammus Aeglefinus

The goal of this study was to gain insight about the impact of intensive fishing on a single haddock (Melanogrammus aeglefinus) stock, and examine the genetic structuring of spatially discrete spawning aggregations in the northwest Atlantic. We analyzed genetic change at four microsatellite loci for Georges Bank haddock over a 40-year time span in which significant changes in demographics and abundances have occurred in the population. Allelic diversities have changed little, indicating that, although the commercial fishery has collapsed, stock sizes have remained large enough to insulate against major reductions in genetic variation due to drift. Results indicate significant genetic divergence among decadally separated samples. Potential causes for these differences include admixture from other spawning regions, fluctuations in the effective number of spawners contributing to a single spawning event, drift, or a combination of these. Examination of discrete spawning aggregations from Georges Bank, Browns Bank, the Scotian Shelf, and Nantucket Shoals indicated significant differences among stocks. Genetic distance based measures supported the clustering of Scotian Shelf, Browns Bank, and Georges Bank haddock to the exclusion of Nantucket Shoals haddock. Haddock spawning on Nantucket Shoals may be genetically discrete from other haddock populations in the northwest Atlantic.

Spawning Time and Egg Stage Duration in Northwest Atlantic Haddock (Melanogrammus aeglefinus) Stocks with Emphasis on Georges and Browns Bank

1989 ◽  
Vol 46 (S1) ◽  
pp. s68-s81 ◽  
Author(s):  
Fred. H. Page ◽  
Kenneth T. Frank
Keyword(s):  
Water Temperature ◽  
Annual Variation ◽  
Incubation Temperature ◽  
Temperature Cycle ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Stage Duration ◽  
Northwest Atlantic ◽  
Spawning Time ◽  
Haddock Melanogrammus Aeglefinus

Literature data was used to examine the hypothesis that variation in the spawning time, defined as the peak in egg abundance, of Northwest Atlantic haddock (Melanogrammus aeglefinus) stocks is explained by water temperature and to derive calibration curves relating incubation temperature to haddock egg stage duration. Spawning times occurred, on average, in March on Georges Bank, late April/early May on Browns Bank, and in June/July on the Grand Banks. Temperatures at peak spawning overlapped considerably but differed in terms of phase in the annual temperature cycle. Inter-annual variation in spawning time of Georges Bank haddock varied by 3 mo and was significantly correlated with water temperature. Browns Bank haddock spawning varied by only 1 mo and was not correlated with water temperature. Egg stage duration varied with incubation temperature. A power curve best described the relationship and was used to estimate the historical, annual variation in haddock egg stage duration which ranged from 10 to 20 d (mean = 16 d) on Georges Bank and from 10 to 30 d (mean = 18 d) on Browns Bank during 1946–80. Collectively, our analysis calls into question the generality of the assumption of constant spawning times for marine fish species and provides essential information for field measurement of haddock egg production rates, mortality, advection, and dispersal.

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.

Recruitment Variability and Its Implication for Managing and Rebuilding the Georges Bank Haddock (Melanogrammus aeglefinus) Stock

1986 ◽  
Vol 43 (4) ◽  
pp. 748-753 ◽  
Author(s):  
William J. Overholtz ◽  
Michael P. Sissenwine ◽  
Stephen H. Clark
Keyword(s):  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Fishing Mortality ◽  
Initial Strategy ◽  
Low Probability ◽  
The Relationship ◽  
Constant Growth ◽  
Spawning Biomass ◽  
Haddock Melanogrammus Aeglefinus ◽  
Stock Recovery

The Georges Bank haddock (Melanogrammus aeglefinus) fishery has fluctuated dramatically since the early 1960's. Abundance declined from the mid-1960's to the mid-1970's, partially recovered, and has declined again since 1980. In general, poor year-classes have been associated with a low spawning biomass although the relationship is variable. The fishery was simulated by using the Baranov catch equation, constant growth and natural mortality, and stochastic levels of recruitment whose probabilities correspond to historic patterns in the stock and recruitment data. Simulations suggest a low probability for stock recovery and improved yield under current conditions (F ≈ 0.5). Recovery time increased with increases in fishing mortality (F), and beyond F = 0.40 recovery is unlikely within 25 yr. With recruitment of a very large year-class (100 million fish) an initial strategy providing for a relatively low level of F(= 0.10) for 3−5 yr, followed by exploitation at historically sustainable levels (F = 0.35), would result in stock recovery. With recruitment of a smaller year-class (50 million fish) low initial levels (F = 0.10) and subsequent management at or near F0.1 (F = 0.26) would be required to initiate stock recovery and reasonable harvest levels in future years.

Dispersal of early life stage haddock (Melanogrammus aeglefinus) as inferred from the spatial distribution and variability in length-at-age of juveniles

1999 ◽  
Vol 56 (12) ◽  
pp. 2350-2361 ◽  
Author(s):  
Nancy L Shackell ◽  
Kenneth T Frank ◽  
Brian Petrie ◽  
David Brickman ◽  
Jennifer Shore
Keyword(s):  
Early Life ◽  
Life Stage ◽  
Circulation Model ◽  
Early Life Stage ◽  
Melanogrammus Aeglefinus ◽  
Bay Of Fundy ◽  
Shelf Area ◽  
Scotian Shelf ◽  
Frequency Distributions ◽  
Haddock Melanogrammus Aeglefinus

In southwestern Nova Scotia, haddock (Melanogrammus aeglefinus) spawning is centered on Browns Bank where the variability of a partial gyre influences the distribution of eggs and larvae. An unknown proportion of each year-class is advected northward to the Bay of Fundy. We examined the variability in length at age 2 as an index of retention during early life. We assumed that early life stages that are retained in the Scotian Shelf area grow more slowly, while those that are advected into the Bay of Fundy grow more quickly. An optimization program was used to estimate the proportions of Scotian Shelf and Bay of Fundy sized components in length at age 2 bimodal frequency distributions for year-classes 1968-1993. The median proportion of Scotian Shelf sized fish was 0.89. A physical circulation model showed that the majority of particles released on Browns Bank drifted towards the Bay of Fundy. Results of the physical model and the size-based index differ partly because the former predicts the fate of passive particles, while the latter is an integrated measure of the proportion of fish retained and surviving. Survival is associated with high wind stress (r = -0.5, p = 0.011, n = 25) implying a higher probability of survival of those retained in the Scotian Shelf region.

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

Evidence for specificity of Steganoderma formosum for its second intermediate host in the Northwest Atlantic

1996 ◽  
Vol 70 (3) ◽  
pp. 215-218 ◽  
Author(s):  
D.J. Marcogliese
Keyword(s):  
Intermediate Host ◽  
Hermit Crabs ◽  
Georges Bank ◽  
Intermediate Hosts ◽  
Scotian Shelf ◽  
Northwest Atlantic ◽  
The Pacific ◽  
Cephalothorax Length ◽  
Second Intermediate Host ◽  
Crangon Septemspinosa

AbstractMetacercariae of Steganoderma formosum Stafford, 1904 infected 17 of 358 Acadian hermit crabs (Pagurus acadianus) on the Scotian Shelf east of Nova Scotia, Canada, in the Northwest Atlantic Ocean in 1989, 1990 and 1995. Overall prevalence and abundance in P. acadianus on the Scotian Shelf were 5% and 0.4 metacercariae per crab, with a maximum intensity of 56. The highest prevalence (34%) and abundance (2.9) were recorded in the winter of 1989. All infected hermit crabs were greater than 9 mm in cephalothorax length. The parasite was not found in Acadian hermit crabs (n = 74) from Georges Bank, nor in any hairy hermit crabs (P. arcuatus and P. pubescens) on the Scotian Shelf (n = 808), on Georges Bank (n = 14), or in the northern Gulf of St. Lawrence (n = 87). A single sand shrimp (Crangon septemspinosa) of 1254 collected from the Scotian Shelf in 1989 and 1990 was infected with a metacercaria of S. formosum. None of 421 pink shrimps (Pandalus spp.) collected from the Scotian Shelf in 1989 and 1995 was infected. Male and female reproductive systems were well developed and spermatozoa were observed in the seminal receptacles of most parasites, suggesting that these metacercariae are progenetic. The distribution of the parasite among potential intermediate hosts suggests that S. formosum demonstrates greater specificity for its second intermediate host in the Northwest Atlantic than it does in the Pacific or in the Northeast Atlantic oceans.

Comment on “Does the fall phytoplankton bloom control recruitment of Georges Bank haddock, Melanogrammus aeglefinus, through parental condition?”Appears in Can. J. Fish. Aquat. Sci. 65: 1076–1086.

2009 ◽  
Vol 66 (5) ◽  
pp. 869-872 ◽  
Author(s):  
Mark R. Payne ◽  
Mark Dickey-Collas ◽  
Richard D.M. Nash
Keyword(s):  
Phytoplankton Bloom ◽  
Uncertain Data ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Alternative Hypotheses ◽  
Parental Condition ◽  
Bloom Control ◽  
Haddock Melanogrammus Aeglefinus ◽  
Sizable Number ◽  
Main Factor

In the paper “Does the fall phytoplankton bloom control recruitment of Georges Bank haddock, Melanogrammus aeglefinus , through parental condition?”, Friedland et al. (Can. J. Fish. Aquat. Sci. 65(6): 1076–1086, 2008) examine a sizable number of hypotheses aiming to explain the recruitment patterns observed in Georges Bank haddock. The authors focus on a correlation between the size of the autumnal phytoplankton bloom and the survivor ratio (recruitment), concluding this to be the main factor determining recruitment, via the mechanism of adult condition at the time of spawning. Here we examine this result in close detail and re-analyse some of the data presented in the paper. We show that the recruitment metric upon which Friedland et al. base their conclusions inadvertently biases the analysis in favour of high recruitment events and against low recruitments. As a consequence, Friedland et al. disregard correlations that are, in fact, significant. Furthermore, we show that the parental condition hypothesis hinges upon a single, highly uncertain data point, without which the correlation is no longer significant. We find that evidence for the parental condition hypothesis is weak, and that in performing the analysis in the chosen manner, Friedland et al. have overlooked alternative hypotheses.

Alimentary tract parasites of haddock (Melanogrammus aeglefinus L.) on the Scotian Shelf

1981 ◽  
Vol 59 (12) ◽  
pp. 2244-2252 ◽  
Author(s):  
J. S. Scott
Keyword(s):  
Alimentary Tract ◽  
Parasite Prevalence ◽  
Melanogrammus Aeglefinus ◽  
Bay Of Fundy ◽  
Scotian Shelf ◽  
Young Of The Year ◽  
Parasite Complex ◽  
Haddock Melanogrammus Aeglefinus ◽  
Hysterothylacium Aduncum ◽  
Biological Tags

Nineteen species of alimentary tract (including gall and swim bladders) parasites were found in haddock (Melanogrammus aeglefinus) on the Scotian Shelf, of which eight species were new Canadian records for haddock. Prevalence ranged up to 82.3% for Hysterothylacium aduncum and 70.9% for Echinorhynchus gadi, the most abundant parasites, with Lepidapedon rachion and Echinorhynchus gadi showing highest intensities (14.9 and 76.5, respectively). Prevalence decreased from summer to winter, was not related to sex of host, but showed geographical variation characterizing different geographical areas. The Bay of Fundy showed higher nematode and lower trematode abundance than the offshore Scotian Shelf which showed general clines in abundance of several species from southwest to northeast. There was no evidence of growth-related change in parasite prevalence in adult fish, but the parasite complex of young-of-the-year haddock indicated planktonic feeding, in contrast with benthic feeding in the adult. Site specificity within the alimentary tract was shown by several species. Echinorhynchus gadi changed its site seasonally. Lepidapedon rachion showed size differentiation in the gut, smaller trematodes occupying more anterior sites than larger. Only two parasite species offer prospects as biological tags, L. rachion and Myxidium bergense, but all may provide evidence of ecological, behavioral, seasonal and developmental changes in the host.

Recruitment to Northwest Atlantic Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) Stocks: Influence of Stock Size and Climate

1987 ◽  
Vol 44 (1) ◽  
pp. 26-39 ◽  
Author(s):  
J. Anthony Koslow ◽  
Keith R. Thompson ◽  
William Silvert
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Reproductive Output ◽  
Atlantic Cod ◽  
Low Frequency ◽  
Melanogrammus Aeglefinus ◽  
Northwest Atlantic ◽  
Biological Variables ◽  
Low Frequency Variability ◽  
Haddock Melanogrammus Aeglefinus

Year-class success of both Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) stocks in the northwest Atlantic exhibits large-scale coherence and low-frequency variability with apparent periodicities of 10–20 yr. Several physical and biological variables in the region exhibit similar large-scale coherence and apparent periodicity. Multiple regression analysis indicates that year-class success in northwest Atlantic cod stocks tends to be associated with large-scale meteorological patterns and offshore winds. Recruitment to most haddock stocks from the Scotian Shelf to Georges Bank is negatively associated with abundance of 0-group mackerel, which may be due to predation over winter and/or to a combination of environmental features including sea-surface temperature, large-scale atmospheric pressure systems, and freshwater outflows. Statistical analyses often did not define a unique set of variables that best predicted fishery recruitment due to widespread intercorrelations among environmental processes and the likelihood that not all relevant processes entered directly into the analyses. There is little evidence that stock reproductive output during the study period was significantly related to year-class success.

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