Growth Of Haddock Research Articles

Effect of environmental factors and density-dependence on somatic growth of Eastern Georges Bank haddock (Melanogrammus aeglefinus)

Haddock (Melanogrammus aeglefinus) is an important commercial fish species in the Northwest Atlantic, with the Eastern Georges Bank population a transboundary resources utilized by both Canada and the United States. With the dramatic increase recruitment of this population in the last decade, in particular concentrations of fish on the eastern portion of the Bank, there has been a precipitous decrease in somatic growth, raising concerns for managers and stakeholders. In this study, the effect of environmental factors and density-dependence on somatic growth of eastern Georges Bank haddock was studied using a 2-step Generalized Additive Model (GAM) regression approach. The biotic and abiotic factors examined in the regression analysis included haddock density, sampling location, local sea surface and bottom temperature, salinity and short time series of phytoplankton bloom statistics. The relative importance of each covariate in the best selected model was investigated using the nested GAMs. We found that density-dependence explained most of the variation in haddock growth, where the impact of temperature varied by season. Though of less model importance, annual winter salinity and phytoplankton bloom magnitude (lagged by one year) also contributed the growth model fits. These relationships have the immediate application of contextualizing the observed change in haddock growth, but may also inform various aspects of the stock assessment process.

The nascent recovery of the Georges Bank haddock stock

World-wide many fish stocks have been depleted by overfishing. In this study, we describe the nascent recovery of the Georges Bank haddock stock. This mainstay of the New England groundfish fishery was overfished for decades prior to mid-1990s and experienced long-term declines in spawning biomass and recruitment. The stock was considered to have collapsed in the early-1990s when a lawsuit by the Conservation Law Foundation led the New England Fishery Management Council (NEFMC) and the National Marine Fisheries Service (NMFS) to take actions to cease overfishing and to recover Georges Bank haddock and other groundfish stocks. Under restrictive management measures, stock size increased 10-fold from 1995 to 2005. In 2003, an exceptionally abundant year class (YC) was produced. Although this YC may rebuild the haddock stock to pre-1930s abundance if properly fished, monitoring changes in life history parameters and recruitment will be important for sustaining stock recovery. Mean weights and sizes at age of adult haddock have decreased in recent years, and compensatory responses of haddock growth and recruitment to changes in stock density are assessed. We discuss some remaining challenges to managing this recovering transboundary resource in a dynamic multispecies fishery.

Estimating growth in haddock larvae Melanogrammus aeglefinus from RNA:DNA ratios and water temperature

Five biochemically based variables (RNA, DNA, protein content, RNA:DNA [R:D] ratio, protein:DNA [pro:DNA] ratio) were evaluated as potential indirect measures of growth in larval haddock Melanogrammus aeglefinus. Larvae were reared in the laboratory from hatch to 47 d post-hatch under temperature (T)-controlled conditions (6, 8, and 10°C) and, to produce a variety of growth rates, were starved or reared at 1 of 3 prey levels. The nucleic acid content of the larvae was measured with a spectrofluorometric microplate assay, and the protein-specific growth rate (SGR,% d -1 ) was estimated from the difference in mean protein content between consecutive sampling intervals. Larval haddock growth rate was best described by R:D or pro:DNA ratios. The growth models developed were: SGR=4.61R:D+ 1.18T- 17.31 (R 2 = 0.52) and SGR = 0.92 pro:DNA + 1.10T- 24.97 (R 2 = 0.52). These models can be used to estimate recent growth of larval haddock collected from both the laboratory and field. A combined haddock/Atlantic cod Gadus morhua growth model was calculated as: SGR = 4.67R:D + 0.96T- 15.30 (R 2 = 0.45). This model will be used to estimate recent growth of haddock and cod larvae collected during a multi-year field sampling effort on Georges Bank.

Age and growth of larval cod and haddock on Georges Bank during 1995 and 1996

Growth rates of larval cod Gadus morhua and haddock Melanogrammus aeglefinus were estimated based on collections in winter and spring of 1995 and 1996 during the US Global Ocean Ecosystem Dynamics (GLOBEC) Georges Bank Program. Growth was determined using length-at-age data derived from otolith increments to indicate age in days from hatching. Growth varied significantly among months and between 1995 and 1996. In general, cod growth exceeded 0.2 mm d -1 and reached a maximum growth rate of 0.7 mm d -1 in May 1996. Haddock growth was also greater than 0.2 mm d -1 with a peak of 0.5 mm d -1 in June 1995. For cod, instantaneous growth rates of 3.3 to 3.5% d -1 were higher than those published previously for the Georges Bank region. Haddock growth was comparable to that of cod in 1995 (3.3% d -1 ), but a higher growth rate for had- dock (3.5% d -1 ) in 1996 was probably due to an under-representation of larger sizes in the data avail- able. Increased size-at-age was associated with higher temperatures for both species; however, the effect of temperature on growth appears to have decreased in May as temperatures exceeded 6°C and approached 8°C. Insufficient numbers of larvae of either species were available in May of 1996 for a similar analysis; however, cod growth during May 1996 was the most rapid observed in this study (0.7 mm d -1 ). This corresponded to a period of high production of suitable food organisms, early stage Calanus finmarchicus, in May 1996 resulting from cooler winter temperatures and late warm- ing after the winter of 1996, suggesting that cooler temperatures favor a prolonged period of food production for larvae and better conditions for growth late in the larval period.

Impact of spectral composition on larval haddock, Melanogrammus aeglefinus L., growth and survival

In a small-scale culture experiment, larval haddock, Melanogrammus aeglefinus L., were raised under various combinations of light quality [blue (470 nm), green (530 nm) or full-spectrum white light] and light intensity [low (0.3–0.4 µmol s−1 m−2) or high (1.7–1.9 µmol s−1 m−2)], and in total darkness (both fed, and starved). Larval growth (0.9% day−1 in standard length; 2.4% day−1 in body area) was not significantly different between any combination of coloured light. At the time of total mortality in the starved treatment, survival was significantly reduced under low intensity, full-spectrum white light (13%) vs. all other coloured light treatments (68%). Larvae raised under both continuous dark treatments (fed and starved) exhibited morphological changes associated with irreversible starvation (point-of-no-return). Lack of a pronounced effect of light quality on larval haddock growth probably results from a combination of plasticity in early larval vision, and enhanced encounter rates between larvae and prey at the relatively high prey densities used in aquaculture.

Comment: Larval Atlantic cod and haddock growth models, metabolism, ingestion, and temperature effects

Discussion 1960 In a rece t article, Leising and Franks (1999) presented detailed individual-based models (IBMs) for larval Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) based on the bioenergetic models of Laurence (1985) for the same species. Using these models, they drew conclusions on the effects of varying prey density, turbulence, and temperature on larval growth rate. However, an error in calculation of metabolism and their choice of a scalar for the effect of temperature on assimilation (Qa, their table 1) may require a revision of Leising and Franks’ (1999) conclusions. The error in estimation of daily metabolic rates originated in Laurence (1985) and was repeated in Werner et al. (1996). In this comment, we provide revisions for the estimation of metabolic costs and suggest that Qa for marine fish larvae should fall in the range of 1.06–1.14 based on our analysis of available literature. We also point to components of the model where compensating errors may occur and additional research is needed.

Reply to Buckley et al.’s "Comment: Larval Atlantic cod and haddock growth models, metabolism, ingestion, and temperature effects"

In reexamining recent modeling work on Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) larvae, Buckley et al.1 conclude that the procedure used in Laurence (1985) to calculate daily metabolic rates may have been incorrect. Buckley et al. suggest that the actual daily metabolic rates should be nearly three times higher for both Atlantic cod and haddock. At the same time, they also point out that total assimilation may be much higher (70% rather than <50%) based on more recent data, including laboratory experiments conducted on larval fish of other species (Kiorboe et al. 1987; Wieser and Medgyesy 1990; Letcher et al. 1996). Besides these points, Buckley et al. suggest that the value of Qa, a temperature-dependent “overall” assimilation term used by Leising and Franks (1999), was unrealistically high (we used a value of 1.6). Instead, Buckley et al. suggest that this value should be closer to 1.07–1.14 based on their analysis of data from several experiments on other species of fish. At the time of creation of our model (Leising and Franks 1999), we used our best estimates of these parameters. However, in light of Buckley et al.’s arguments, we agree that their estimates for these parameters may be more appropriate for Atlantic cod and haddock larvae. We therefore reran our model for Atlantic cod only using their suggested parameters to determine the impact on our model results, with specific attention to the effects of temperature versus food availability.

Reply to Buckley et al.'s "Comment: Larval Atlantic cod and haddock growth models, metabolism, ingestion, and temperature effects"

Reply to Buckley et al.'s "Comment: Larval Atlantic cod and haddock growth models, metabolism, ingestion, and temperature effects"

Comment: Larval Atlantic cod and haddock growth models, metabolism, ingestion, and temperature effects

Comment: Larval Atlantic cod and haddock growth models, metabolism, ingestion, and temperature effects

Variability in growth rates of larval haddock in the northern North Sea

The large‐scale distribution of haddock (Melanogrammus aeglefinus) larvae in the northern North Sea was mapped in a grid survey carried out in late April 1996. A drifting buoy was deployed in the centre of one of the areas of concentration of larvae located off the east coast of the Shetland Isles, where intensive sampling was carried out for ≈ 10 days. Daily larval haddock growth variability, estimated from otolith microstructure analysis, was independent of the measured variability of the physical and biological environment of the larvae. The survey coincided with the onset of the spring plankton production bloom, and a likely explanation for the absence of environmental effects on larval growth was high food availability and larval feeding rates. Nevertheless, differences in growth were observed between cohorts, with larvae hatched later in the spring displaying higher growth at age than those hatched earlier. Particle‐tracking modelling suggested that differences in temperature history between cohorts, on their own or compounded by a potential interaction between temperature and the development of plankton production, may explain the higher growth rate of the larvae hatched later in the season.

Investigations into the Growth of Haddock, Melanogrammus Aeglefinus (L) and Whiting, Merlangius Merlangus (L) in Aquaria

Investigations into the Growth of Haddock, Melanogrammus Aeglefinus (L) and Whiting, Merlangius Merlangus (L) in Aquaria

Mesh Selection and Apparent Growth of Haddock

Mesh Selection and Apparent Growth of Haddock Get access Rodney Jones Rodney Jones Marine LaboratoryAberdeen Search for other works by this author on: Oxford Academic Google Scholar ICES Journal of Marine Science, Volume 25, Issue 2, March 1960, Pages 177–184, https://doi.org/10.1093/icesjms/25.2.177 Published: 01 March 1960