Environmental and fishing limitations to the rebuilding of the northern Gulf of St. Lawrence cod stock (Gadus morhua)

2011 ◽  
Vol 68 (4) ◽  
pp. 618-631 ◽  
Author(s):  
Yvan Lambert
Keyword(s):  
Life History ◽  
Gadus Morhua ◽  
Life History Traits ◽  
Atlantic Cod ◽  
Negative Impact ◽  
Reproductive Potential ◽  
Reproductive Rate ◽  
Fishing Mortality ◽  
Recent Period ◽  
Instantaneous Rate

Time series of life history traits determining the reproductive potential and productivity of Atlantic cod ( Gadus morhua ) in the northern Gulf of St. Lawrence (nGSL) were obtained for the period covering the collapse and failure of the stock to recover. Decreasing trends in these traits were observed under unfavourable oceanographic conditions, with lowest values reached in the early 1990s. These changes had a negative impact on reproductive rate and instantaneous rate (r) of population growth. Estimates of r used as a proxy of stock productivity were negative when the stock collapsed, indicating that the biomass would have decreased even without fishing. Population abundance projections for the recent period suggest a potential increase in population size of 7.3% per year, with a doubling time of 10.5 years in the absence of exploitation and a near 0% rate with current fishing mortality, indicating that present harvesting does not allow any rebuilding of the stock. Given the similarities in environmental conditions and key life history traits, the situation in the nGSL might reflect the state of many northwest Atlantic cod stocks.

Paternal effects on early life history traits in Northwest Atlantic cod, Gadus morhua

2013 ◽  
Vol 29 (3) ◽  
pp. 623-629 ◽  
Author(s):  
M.-M. Kroll ◽  
M. A. Peck ◽  
I. A. E. Butts ◽  
E. A. Trippel
Keyword(s):  
Life History ◽  
Early Life ◽  
Gadus Morhua ◽  
Life History Traits ◽  
Atlantic Cod ◽  
Early Life History ◽  
Paternal Effects ◽  
Northwest Atlantic

Life history consequences of overexploitation to population recovery in Northwest Atlantic cod (Gadus morhua)

2005 ◽  
Vol 62 (4) ◽  
pp. 824-832 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Life History ◽  
Population Growth ◽  
Gadus Morhua ◽  
Life History Traits ◽  
Atlantic Cod ◽  
Hatching Rate ◽  
Northwest Atlantic ◽  
Annual Population ◽  
Age Structured ◽  
Negative Impacts

Changes to life history traits are often concomitant with prolonged periods of exploitation. In the Northwest Atlantic, 30- to 40-year declines of more than 90% of Atlantic cod (Gadus morhua) have been associated with significant reductions in age and length at maturity, changes most parsimoniously explained as genetic responses to fishing. Increased survival costs of reproduction associated with earlier maturity, resulting in higher natural mortality and shorter life span, negatively affect population growth rate and rate of recovery. Coupled with lower hatching rate among first-time spawners and smaller size at maturity, a modest reduction in age from 6 to 4 years can reduce annual population growth in Atlantic cod by 25%–30%, based on the output of a stochastic, age-structured life history model. Earlier maturity more than doubles the probability of negative population growth every generation. These results underscore the potential for fishing-induced changes to life history traits alone to generate slow or negligible recovery in marine fishes, exacerbating negative impacts on population growth resulting from ecosystem-level alterations to interspecific competition and predation.

Genetic variation in plasticity of life-history traits between Atlantic cod (Gadus morhua) populations exposed to contrasting thermal regimes

2016 ◽  
Vol 94 (4) ◽  
pp. 257-264 ◽  
Author(s):  
Rebekah A. Oomen ◽  
Jeffrey A. Hutchings
Keyword(s):  
Genetic Variation ◽  
Life History ◽  
Gadus Morhua ◽  
Life History Traits ◽  
Energy Savings ◽  
Atlantic Cod ◽  
Common Garden ◽  
Cold Temperatures ◽  
Thermal Environments ◽  
Thermal Regimes

We employed common-garden experiments to test for genetic variation in responses of larval life-history traits to temperature between two populations of Atlantic cod (Gadus morhua L., 1758) that naturally experience contrasting thermal environments during early life due to spatial and temporal differences in spawning. Southern Gulf of St. Lawrence cod larvae experienced faster growth in warmer water and low, uniform survival across all experimental temperatures (3, 7, 11 °C), consistent with previous studies on this spring-spawning population. In contrast, larvae from fall-spawning Southwestern Scotian Shelf cod collected near Sambro, Nova Scotia, lacked plasticity for growth but experienced much lower survival at higher temperatures. Phenotypes that are positively associated with fitness were observed at temperatures closest to those experienced in the wild, consistent with the hypothesis that these populations are adapted to local thermal regimes. The lack of growth plasticity observed in Sambro cod might be due to costly maintenance of plasticity in stable environments or energy savings at cold temperatures. However, additional experiments need to be conducted on Sambro cod and other fall-spawning marine fishes to determine to what extent responses to projected changes in climate will differ among populations.

Effects of temperature on life history set the sensitivity to fishing in Atlantic cod Gadus morhua

2014 ◽  
Vol 514 ◽  
pp. 217-229 ◽  
Author(s):  
HY Wang ◽  
LW Botsford ◽  
JW White ◽  
MJ Fogarty ◽  
F Juanes ◽  
...  
Keyword(s):  
Life History ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Effects Of Temperature

Natural mortality from poor condition in Atlantic cod (Gadus morhua)

2000 ◽  
Vol 57 (4) ◽  
pp. 826-836 ◽  
Author(s):  
Jean-Denis Dutil ◽  
Yvan Lambert
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Negative Impact ◽  
Fish Muscle ◽  
Early Summer ◽  
Wild Fish ◽  
Natural Mortality ◽  
Muscle Lactate ◽  
Lactate Dehydrogenase Activity ◽  
Poor Condition

The extent of energy depletion was assessed in Atlantic cod (Gadus morhua) in spring and early summer (1993-1995) to assess relationships between poor condition and natural mortality. Several indices of condition were compared in wild fish in the northern Gulf of St. Lawrence and in fish exposed to a prolonged period of starvation in laboratory experiments. Discriminant analyses classified only a small fraction of the wild fish as similar to cod that did not survive and a much larger fraction as similar to cod that survived starvation. This percentage increased from April to May and peaked in June 1993 and 1994. Condition factor and muscle somatic index allowed a clear distinction between live and dead fish. Muscle lactate dehydrogenase activity suggested that cod had experienced a period of negative growth early in 1993, 1994, and 1995. Fish classified as similar to starved individuals were characterized by a higher gonad to liver mass ratio than others. Reproduction may have a negative impact on survival not only in spring but also later into summer, as some individuals were found not to have recovered by late summer. This study shows that natural mortality from poor condition contributed to lower production in the early 1990s.

scholarly journals Life history and habitat do not mediate temporal changes in body size due to climate warming in rodents

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9792
Author(s):  
Aluwani Nengovhela ◽  
Christiane Denys ◽  
Peter J. Taylor
Keyword(s):  
Life History ◽  
Body Size ◽  
Climate Warming ◽  
Life History Traits ◽  
Vegetation Type ◽  
Reproductive Rate ◽  
Temporal Changes ◽  
Temporal Response ◽  
Extrinsic Factors ◽  
African Species

Temporal changes in body size have been documented in a number of vertebrate species, with different contested drivers being suggested to explain these changes. Among these are climate warming, resource availability, competition, predation risk, human population density, island effects and others. Both life history traits (intrinsic factors such as lifespan and reproductive rate) and habitat (extrinsic factors such as vegetation type, latitude and elevation) are expected to mediate the existence of a significant temporal response of body size to climate warming but neither have been widely investigated. Using examples of rodents, we predicted that both life history traits and habitat might explain the probability of temporal response using two tests of this hypothesis. Firstly, taking advantage of new data from museum collections spanning the last 106 years, we investigated geographical and temporal variation in cranial size (a proxy for body size) in six African rodent species of two murid subfamilies (Murinae and Gerbillinae) of varying life history, degree of commensality, range size, and habitat. Two species, the commensal Mastomys natalensis, and the non-commensal Otomys unisulcatus showed significant temporal changes in body size, with the former increasing and the latter decreasing, in relation with climate warming. Commensalism could explain the increase in size with time due to steadily increasing food availability through increased agricultural production. Apart from this, we found no general life history or habitat predictors of a temporal response in African rodents. Secondly, in order to further test this hypothesis, we incorporated our data into a meta-analysis based on published literature on temporal responses in rodents, resulting in a combined dataset for 50 species from seven families worldwide; among these, 29 species showed no significant change, eight showed a significant increase in size, and 13 showed a decline in size. Using a binomial logistic regression model for these metadata, we found that none of our chosen life history or habitat predictors could significantly explain the probability of a temporal response to climate warming, reinforcing our conclusion based on the more detailed data from the six African species.

scholarly journals Regional changes in vertebra morphology during ontogeny reflect the life history of Atlantic cod (Gadus morhua L.)

2013 ◽  
Vol 222 (6) ◽  
pp. 615-624 ◽  
Author(s):  
Per G. Fjelldal ◽  
Geir K. Totland ◽  
Tom Hansen ◽  
Harald Kryvi ◽  
Xiyuan Wang ◽  
...  
Keyword(s):  
Life History ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
History Of

scholarly journals Density Dependence, Evolutionary Optimization, and the Diversification of Avian Life Histories

The Condor ◽  
2000 ◽  
Vol 102 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Robert E. Ricklefs
Keyword(s):  
Life History ◽  
Life Table ◽  
Life Histories ◽  
Life History Traits ◽  
Evolutionary Ecology ◽  
Reproductive Rate ◽  
Empirical Modeling ◽  
Adult Survival ◽  
Life History Variation ◽  
Evolutionary Response

Abstract Although we have learned much about avian life histories during the 50 years since the seminal publications of David Lack, Alexander Skutch, and Reginald Moreau, we still do not have adequate explanations for some of the basic patterns of variation in life-history traits among birds. In part, this reflects two consequences of the predominance of evolutionary ecology thinking during the past three decades. First, by blurring the distinction between life-history traits and life-table variables, we have tended to divorce life histories from their environmental context, which forms the link between the life history and the life table. Second, by emphasizing constrained evolutionary responses to selective factors, we have set aside alternative explanations for observed correlations among life-history traits and life-table variables. Density-dependent feedback and independent evolutionary response to correlated aspects of the environment also may link traits through different mechanisms. Additionally, in some cases we have failed to evaluate quantitatively ideas that are compelling qualitatively, ignored or explained away relevant empirical data, and neglected logical implications of certain compelling ideas. Comparative analysis of avian life histories shows that species are distributed along a dominant slow-fast axis. Furthermore, among birds, annual reproductive rate and adult mortality are directly proportional to each other, requiring that pre-reproductive survival is approximately constant. This further implies that age at maturity increases dramatically with increasing adult survival rate. The significance of these correlations is obscure, particularly because survival and reproductive rates at each age include the effects of many life-history traits. For example, reproductive rate is determined by clutch size, nesting success, season length, and nest-cycle length, each of which represents the outcome of many different interactions of an individual's life-history traits with its environment. Resolution of the most basic issues raised by patterns of life histories clearly will require innovative empirical, modeling, and experimental approaches. However, the most fundamental change required at this time is a broadening of the evolutionary ecology paradigm to include a variety of alternative mechanisms for generating patterns of life-history variation.

The influence of maternal effects in larval survival on fishery harvest reference points for two life-history patterns

2014 ◽  
Vol 71 (1) ◽  
pp. 151-161 ◽  
Author(s):  
Paul D. Spencer ◽  
Sarah B.M. Kraak ◽  
Edward A. Trippel
Keyword(s):  
Life History ◽  
Pacific Ocean ◽  
Maternal Effects ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Larval Survival ◽  
Reference Points ◽  
Life History Pattern ◽  
Gadus Macrocephalus ◽  
Potential Interactions

Increased larval viability with increased spawner age (i.e., maternal effects) have been observed in Atlantic cod (Gadus morhua) and Pacific rockfish (Sebastes spp.) stocks. Analytical results from a Beverton–Holt recruitment model indicate density-independent maternal effects affected the relative stock productivity and fishing rate reference points. We simulated populations based on Pacific cod (Gadus macrocephalus) and Pacific ocean perch (Sebastes alutus) to explore how estimates of reference points Fmsy and Fcrash are affected by maternal effects and potential interactions with life-history pattern, recruitment autocorrelation, and exploitation rate. Estimates of Fmsy and Fcrash were made from populations with maternal effects using either total larvae (proportional to eggs) or viable larvae (incorporating the maternal effect). Maternal effects have the largest impact upon estimated population productivity at high fishing rates. Estimates of Fmsy and Fcrash for cod were also affected by autocorrelated recruitment variability because of their reduced longevity compared with Pacific ocean perch. These results suggest the importance of evaluating the influence of maternal effects on estimated stock productivity on a case-by-case basis, particularly for depleted stocks composed of relatively young spawners.

scholarly journals Life History and Host Preference of Trichopria drosophilae from Southern China, One of the Effective Pupal Parasitoids on the Drosophila Species

Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 103 ◽  
Author(s):  
Chuandong Yi ◽  
Pumo Cai ◽  
Jia Lin ◽  
Xuxiang Liu ◽  
Guofu Ao ◽  
...  
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Southern China ◽  
Reproductive Potential ◽  
Drosophila Species ◽  
Choice Test ◽  
Parasitization Rate ◽  
Pupal Parasitoids ◽  
Lifetime Number ◽  
The Mean

This study aims to evaluate several life-history traits of a T. drosophilae population from southern China and its parasitic preference of three Drosophila species. For mated T. drosophilae females, the mean oviposition and parasitization period were 27.20 and 37.80 d, respectively. The daily mean parasitization rate was 59.24% per female and the lifetime number of emerged progeny was 134.30 per female. Trichopria drosophilae females survived 37.90 and 71.61 d under host-provided and host-deprived conditions, respectively. To assess the potential for unmated reproduction in T. drosophilae, the mean oviposition and parasitization period of unmated females was 22.90 and 47.70 d, respectively. They had a daily mean parasitization rate of 64.68%, produced a total of 114.80 offspring over their lifetime, and survived 52 d. Moreover, T. drosophilae showed a preference towards D. suzukii based on the total number of emerged offspring under a choice test. Our findings indicate that T. drosophilae from southern China appears to be suitable for the control of D. suzukii in invaded areas, due to its reproductive potential.

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