scholarly journals Response of Scotian Shelf silver hake (Merluccius bilinearis) to environmental variability

2018 ◽  
Vol 28 (3) ◽  
pp. 256-272 ◽  
Author(s):  
Daniel Reed ◽  
Stéphane Plourde ◽  
Adam Cook ◽  
Pierre Pepin ◽  
Benoit Casault ◽  
...  
Keyword(s):  
Environmental Variability ◽  
Scotian Shelf ◽  
Silver Hake ◽  
Merluccius Bilinearis

Behavioral inferences from regulatory observer data: catch rate variation in the Scotian Shelf silver hake (Merluccius bilinearis) fishery

1999 ◽  
Vol 56 (2) ◽  
pp. 288-296 ◽  
Author(s):  
D M Gillis
Keyword(s):  
Interference Competition ◽  
Temporal Trends ◽  
Catch Rate ◽  
Rate Variation ◽  
Scotian Shelf ◽  
Apparent Contradiction ◽  
Fishing Vessels ◽  
Catch Rates ◽  
Silver Hake ◽  
Merluccius Bilinearis

The detailed spatial and temporal data collected for the regulation of the silver hake (Merluccius bilinearis) fishery on the Scotian Shelf provide a unique opportunity to test hypotheses about variability in catch rates on the scale of individual trawls. I used these data to examine vessel interactions and long-term temporal trends in catchability. An index of course linearity, derived from observed positions, times, and speeds of fishing vessels, indicated that interference competition was present in the fishery. However, catch rate did not decline with local vessel density. This apparent contradiction is consistent with fleet dynamic theory and suggests that the direct examination of catch rates is a poor test for interference in the retrospective analysis of fisheries data. The study of extended periods of high, localized fishing activity revealed a cycle in catch rates with periods of about 6 days. Such periods may represent an interaction between tidal, diel, and (or) technological factors. Although more study is required to identify the cause of these cycles, their existence should be considered in the design of surveys and other population studies using catch and effort data.

Growth variation and water mass associations of larval silver hake (Merluccius bilinearis) on the Scotian Shelf

2000 ◽  
Vol 57 (8) ◽  
pp. 1728-1738 ◽  
Author(s):  
Jennifer A Jeffrey ◽  
Christopher T Taggart
Keyword(s):  
Water Mass ◽  
Age And Growth ◽  
Scotian Shelf ◽  
Growth And Survival ◽  
Growth Variability ◽  
Wet Biomass ◽  
Growth Variation ◽  
Silver Hake ◽  
Age Relations ◽  
Merluccius Bilinearis

Otolith microstructure is shown to be ideal for assessing age and growth in silver hake (Merluccius bilinearis) larvae and is used to examine growth among individuals and cohorts. Larvae collected from Western Bank, Scotian Shelf, in September, October, and November 1997 defined three monthly cohorts identified using inferred hatch dates. Total length-at-age relations did not differ between the September and October cohorts despite substantial differences in growing degree-day (435 versus 318°C·d) and zooplankton (potential prey index) wet biomass (0.15 versus 0.27 g·m-3). Larvae collected off-bank in September exhibited a growth advantage of >0.10 mm·d-1 relative to larvae collected on-bank. Greater variability in growth rate within cohorts and among water masses implies that cohort-averaged growth and survival (based on growth) estimates can be biased by overrepresentation of a single water mass. The focus on growth variability, and its relationship to survival, should be on individuals within cohorts and not on cohort-averaged estimates. We hypothesize that growth, and perhaps survival, in silver hake larvae on the Scotian Shelf is most easily explained by variation in physical oceanographic processes.

Multiple-Frequency Acoustic Backscattering and Zooplankton Aggregations in the Inner Scotian Shelf Basins

1991 ◽  
Vol 48 (3) ◽  
pp. 340-355 ◽  
Author(s):  
N. A. Cochrane ◽  
D. Sameoto ◽  
A. W. Herman ◽  
J. Neilson
Keyword(s):  
Target Strength ◽  
Scotian Shelf ◽  
Migration Patterns ◽  
Acoustic Backscattering ◽  
Large Populations ◽  
Order Of Magnitude ◽  
Silver Hake ◽  
Merluccius Bilinearis ◽  
Domain Dependence

Acoustic backscatter observations at 12, 50, and 200 kHz in the inner Scotian Shelf basins reveal large populations of silver hake (Merluccius bilinearis) and its principal prey, the euphausiid Meganyctiphanes norvegica. Multichannel sonar colour imagery facilitates separation of fish from euphausiids and delineation of their separate diurnal migration patterns. Silver hake acoustic abundances are consistent with midwater trawl sampling. Acoustic column densities for mature M. norvegica of approximately 1000/m2 exceed net sampling column densities by over 1 order of magnitude indicating strong net avoidance. Numerical simulation of euphausiid backscattering using a fluid cylinder model and natural distribution of scatterer orientations yields an approximate 20 log L target strength length dependence and little frequency domain dependence in the "geometric" scattering regime. Quantitative interpretation of euphausiid scattering in situ must account for randomness in their orientations.

Storage Life of Refrozen Silver Hake (Merluccius bilinearis) Processed as Fillets am Minced Flesh from Thawed, Stored, Round-Frozen Fish

1977 ◽  
Vol 34 (12) ◽  
pp. 2369-2373 ◽  
Author(s):  
Doris Fraser Hiltz ◽  
D. H. North ◽  
Barbara Smith Lall ◽  
R. A. Keith
Keyword(s):  
Key Words ◽  
Frozen Storage ◽  
Storage Life ◽  
Freeze Thaw ◽  
Acceptable Quality ◽  
Frozen Fish ◽  
Silver Hake ◽  
Merluccius Bilinearis ◽  
Protein Extractability

Refrozen silver hake (Merluccius bilinearis), processed as fillets and minced flesh after thawing of stored round fish that had been frozen within 14 h of capture, underwent rapid deterioration during storage at −18 °C compared with once-frozen control materials from the same lot of fish. The estimated maximum storage life of silver hake refrozen as fillets after 3 and 6 mo storage of the round fish at −25 °C was reduced to about 4.5 and 1 mo, respectively, from 10 mo for once-frozen control fillets. Quality of the refrozen materials immediately after thawing and refreezing was similar to that of the round-frozen fish, except after 6 mo, where some initial deterioration occurred, particularly in minced flesh. Minced flesh was more unstable in frozen storage than fillets. In all once- and twice-frozen materials, formation of dimethylamine occurred concomitantly with decrease in protein extractability. Round-frozen fish underwent no loss in protein extractability during 6 mo storage at −25 °C, but some lipid hydrolysis occurred. These results suggest that the freeze–thaw–refreeze process as applied to silver hake will yield a final product of acceptable quality provided that storage of the round fish does not exceed 3–4 mo and that the refrozen materials are marketed within a month after processing. Key words: silver hake, Merluccius bilinearis, refrozen storage, dimethylamine, minced flesh

Seasonal and Geographic Variation in the Species Composition and Size of Prey Consumed by Grey Seals (Halichoerus grypus) on the Scotian Shelf

1993 ◽  
Vol 50 (8) ◽  
pp. 1768-1778 ◽  
Author(s):  
W. D. Bowen ◽  
J. W. Lawson ◽  
B. Beck
Keyword(s):  
Atlantic Cod ◽  
Halichoerus Grypus ◽  
Scotian Shelf ◽  
Sand Lance ◽  
Atlantic Mackerel ◽  
Relative Contribution ◽  
Wet Weight ◽  
The Mean ◽  
Silver Hake ◽  
Commercial Size

The grey seal (Halichoerus grypus) population on the Scotian Shelf has grown significantly over the past 20 yr, thus increasing the potential for competitive interactions between grey seals and fisheries. The relative contribution (percent wet weight) and size of prey eaten were estimated from otoliths and squid beaks recovered from 143 stomachs that contained food of the 528 collected from 1988 to 1990. Although 22 taxa were found, only four species (Atlantic herring, silver hake, Atlantic cod, and squid) accounted for 80% of the estimated weight of food eaten. The mean length of prey eaten ranged from 19 to 35 cm for six species. Only 17% of the cod and none of the pollock and squid eaten were of the length taken in commercial fisheries. However, about 80% of the silver hake and herring eaten were of commercial size. Offshore at Sable Island, northern sand lance, silver hake, and squid (in order of importance) accounted for 86.1% of the wet weight ingested by seals during summer; sand lance and cod accounted for 96.1% of prey eaten in winter. At inshore locations, herring, cod, and pollock made up 90% of the diet in summer; Atlantic mackerel, cod, squid, and herring made up 83% of the diet in winter.

scholarly journals A zero percent plastic ingestion rate by silver hake (Merluccius bilinearis) from the south coast of Newfoundland, Canada

2018 ◽  
Vol 131 ◽  
pp. 267-275 ◽  
Author(s):  
France Liboiron ◽  
Justine Ammendolia ◽  
Jacquelyn Saturno ◽  
Jessica Melvin ◽  
Alex Zahara ◽  
...  
Keyword(s):  
Ingestion Rate ◽  
South Coast ◽  
The South ◽  
Silver Hake ◽  
Merluccius Bilinearis

Apparent digestibility coefficients of raw ground, acid and fermented silver hake (Merluccius bilinearis) feedstuffs for mink and an evaluation of the storage stability of the silages

1999 ◽  
Vol 79 (3) ◽  
pp. 375-381 ◽  
Author(s):  
M. B. White ◽  
D. M. Anderson ◽  
K. I. Rouvinen
Keyword(s):  
Formic Acid ◽  
Storage Stability ◽  
Storage Period ◽  
Apparent Digestibility ◽  
Standard Type ◽  
Randomized Design ◽  
Gross Energy ◽  
Silver Hake ◽  
Merluccius Bilinearis

A 3 × 4 factorial design experiment was conducted to determine digestibility coefficients (DC) of dry matter (DM), crude protein (CP), crude fat (CF), gross energy (GE) and amino acids (AA) in raw ground silver hake (RGSH), acid (ASHS) and fermented (FSHS) silver hake silages for mink. The ASHS was prepared with the addition of 2.5% (wt:wt) formic acid (85% concentration) and 200 ppm antioxidant (ethoxyquin) to the raw ground fish. The FSHS was produced with the addition of 1% Marisil® (Finn Sugar), 15% extruded wheat and 1% (wt:wt) formic acid (conc. 85%) to the raw ground fish. Twelve mature standard type male mink were confined to metabolism cages during the digestibility trial, which consisted of three experimental periods comprised of a 6-d adjustment period, followed by a 5-d collection period. Based on the total collection (TC) method and with graded levels (0, 15, 30 and 45%) of the test feedstuffs in the experimental diets, nutrient digestibilities in the pure feedstuffs were determined using a mathematical regression technique. The apparent digestibility (AD) of DM, CP, CF and GE were RGSH: 88.4, 93.6, 99.2 and 94.7%; ASHS: 90.6, 85.8, 96.1 and 87.2% and FSHS: 77.7, 84.5, 99.2 and 86.1%, respectively. The AD of all the AAs, except proline, in the RGSH was significantly higher (P < 0.05) than that in the ASHS and FSHS. A quality evaluation of the silages was conducted in a completely randomized design with two replications to determine storage stability of the silages, on 10 different sampling days, (3 sampling days for AAs), over the storage period. Quality of the silages was stable up to 90 days for the ASHS and 180 days FSHS based on increases in pH and total volatile nitrogen (TVN) content and decreases in N and AA content. The silver hake feedstuffs would provide a good source of highly digestible nutrients for mink and should be considered as opportunity feeds for these animals. Key words: Apparent digestibility, fish by-products, mink, silage, silage quality, silver hake

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