Nutritional Status of Field-Collected Haddock (Melanogrammus aeglefinus) Larvae from Southwestern Nova Scotia: An Assessment based on Morphometric and Vertical Distribution Data

1989 ◽  
Vol 46 (S1) ◽  
pp. s125-s133 ◽  
Author(s):  
Kenneth T. Frank ◽  
Jeff K. McRuer
Keyword(s):  
Nova Scotia ◽  
Nutritional Status ◽  
Good Condition ◽  
Field Studies ◽  
Melanogrammus Aeglefinus ◽  
Larval Abundance ◽  
Distribution Data ◽  
Poor Condition ◽  
The North ◽  
Haddock Melanogrammus Aeglefinus

The nutritional status of haddock (Melanogrammus aeglefinus) larvae was evaluated during May 1986 over a grid of stations exhibiting variable hydrographic conditions in southwestern Nova Scotia. Over the shallow, wellmixed regions of both the nearshore and western cap of Browns Bank, post-yolk sac haddock larvae exhibited below-average values of Fulton's K ((W/SL3) × 100, W = weight; SL = standard length) with a correspondingly high proportion of larvae in poor condition (> 70%). Conversely, larvae in good condition predominated in the deeper, stratified waters on the eastern cap of the Bank and at off-bank stations to the north along the 100-m isobath. These results agree with published field studies that used either histological or biochemical criteria to evaluate larval condition. Larvae in poor condition also exhibited surface-skewed and frequently bimodal depth profiles in contrast with the unimodal profiles centred at middepth of larvae in good condition, a result consistent with the hypothesis that buoyancy increases in starving larvae. The typically low correlation between larval abundance and recruitment may arise from use of abundance data uncorrected for the proportion of larvae in poor condition. Prorating larval survey data by using proxy variables such as stratification intensity may ultimately increase their predictive utility.

Survival and Abundance of Young Atlantic Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) as Indicators of Year-class Strength

1989 ◽  
Vol 46 (S1) ◽  
pp. s171-s182 ◽  
Author(s):  
Steven E. Campana ◽  
Kenneth T. Frank ◽  
Peter C. F. Hurley ◽  
Peter A. Koeller ◽  
Fred H. Page ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Larval Mortality ◽  
Larval Growth ◽  
Melanogrammus Aeglefinus ◽  
Larval Abundance ◽  
Life History Stage ◽  
Spawning Site ◽  
Haddock Melanogrammus Aeglefinus

To identify the life history stage(s) most influential in determining yearclass strength, we constructed and analyzed survival curves of the 1983, 1984, and 1985 cohorts of cod and haddock off Southwest Nova Scotia relative to their physical and biological environment. Relative abundance of each Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) yearclass was not reflected by egg or larval abundance in any year examined. However, abundance of both pelagic and settled juveniles did appear to reflect yearclass strength. Egg and larval mortality could not be consistently linked with advection from the spawning site, and did not covary with subsequent recruitment. In both species, mortality between the larval and juvenile stage was inversely correlated with yearclass strength, but sources of the mortality could not be identified. Larval growth was inversely related to mortality of the early larval stage and independent of larval abundance. However, juvenile growth was proportional to mortality and inversely related to abundance. Despite early life coexistence and similarities in spawning time and location, the relative yearclass strengths of cod and haddock in Southwest Nova Scotia were different, suggesting that the timing of local physical and biological events may play an important role in the recruitment success of these stocks.

Distribution and Abundance of Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) Eggs and Larvae in the Waters off Southwest Nova Scotia

1989 ◽  
Vol 46 (S1) ◽  
pp. s103-s112 ◽  
Author(s):  
Peter C. F. Hurley ◽  
Steven E. Campana
Keyword(s):  
Nova Scotia ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Melanogrammus Aeglefinus ◽  
Eggs And Larvae ◽  
Haddock Melanogrammus Aeglefinus ◽  
Egg Abundance

Synoptic ichthyoplankton surveys conducted at monthly intervals during the winter–spring of 1983–85 were used to determine the location, timing, and magnitude of spawning by haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) off southwest Nova Scotia. There was a marked similarity in the spawning locations of the two species: primary spawning occurred on Browns Bank, although lower levels of spawning were observed on adjacent banks and in the inshore region. Cod egg abundance peaked in April in all years, while that of haddock varied between April–June.

scholarly journals Population comparison of right whale body condition reveals poor state of the North Atlantic right whale

2020 ◽  
Vol 640 ◽  
pp. 1-16 ◽  
Author(s):  
F Christiansen ◽  
SM Dawson ◽  
JW Durban ◽  
H Fearnbach ◽  
CA Miller ◽  
...  
Keyword(s):  
Body Condition ◽  
North Atlantic ◽  
Good Condition ◽  
The Body ◽  
North Atlantic Right Whale ◽  
Poor Condition ◽  
Right Whale ◽  
The North ◽  
The Poor ◽  
The North Atlantic

The North Atlantic right whale Eubalaena glacialis (NARW), currently numbering <410 individuals, is on a trajectory to extinction. Although direct mortality from ship strikes and fishing gear entanglements remain the major threats to the population, reproductive failure, resulting from poor body condition and sublethal chronic entanglement stress, is believed to play a crucial role in the population decline. Using photogrammetry from unmanned aerial vehicles, we conducted the largest population assessment of right whale body condition to date, to determine if the condition of NARWs was poorer than 3 seemingly healthy (i.e. growing) populations of southern right whales E. australis (SRWs) in Argentina, Australia and New Zealand. We found that NARW juveniles, adults and lactating females all had lower body condition scores compared to the SRW populations. While some of the difference could be the result of genetic isolation and adaptations to local environmental conditions, the magnitude suggests that NARWs are in poor condition, which could be suppressing their growth, survival, age of sexual maturation and calving rates. NARW calves were found to be in good condition. Their body length, however, was strongly determined by the body condition of their mothers, suggesting that the poor condition of lactating NARW females may cause a reduction in calf growth rates. This could potentially lead to a reduction in calf survival or an increase in female calving intervals. Hence, the poor body condition of individuals within the NARW population is of major concern for its future viability.

Sign in / Sign up

Export Citation Format

Share Document