scholarly journals Stronger density-dependent growth of Japanese sardine with lower food availability: Comparison of growth and zooplankton biomass between a historical and current stock-increase period in the western North Pacific

2021 ◽  
Author(s):  
Yasuhiro Kamimura ◽  
Kazuaki Tadokoro ◽  
Sho Furuichi ◽  
Ryuji Yukami
Keyword(s):  
Density Dependence ◽  
Food Availability ◽  
North Pacific ◽  
Western North Pacific ◽  
Fish Population ◽  
Japanese Sardine ◽  
Density Dependent ◽  
Mesozooplankton Biomass ◽  
Current Period ◽  
Dependent Growth

Density dependence is a fundamental concept for fish population dynamics. Although density-dependent growth and maturity among older juveniles and adults is important for regulating fish population size and for fisheries management, the mechanism of density dependence for marine fishes remains unclear. Here, we examined changes in Japanese sardine growth with increasing abundance beginning in the 2010s and how the current pattern of density-dependent growth differs from that of a previous stock-increase period from the 1970s to early 1980s. During the current period of increasing abundance, mean standard length has already dropped to the lowest level yet observed and growth has declined more sharply with increased abundance than in the 1970s and 1980s. Mesozooplankton biomass in July in the summer feeding grounds was also lower during the current period. Therefore, our results suggest that summer food availability in the western North Pacific controls the strength of density-dependent growth. A lower carrying capacity for Japanese sardine could account for the stronger density dependence of growth observed in the 2010s; this indicates that future Japanese sardine abundance might not increase as much as in the 1980s unless food availability improves.

scholarly journals Evaluation of the Shepherd and Cushing (1980) model of density-dependent survival: a case study using striped bass (Morone saxatilis) larvae in the Potomac River, Maryland, USA

2003 ◽  
Vol 60 (6) ◽  
pp. 1275-1287 ◽  
Author(s):  
Edward S Rutherford ◽  
Kenneth A Rose ◽  
James H Cowan
Keyword(s):  
Regression Model ◽  
Striped Bass ◽  
Carrying Capacity ◽  
Field Data ◽  
Larval Growth ◽  
Fish Population ◽  
Potomac River ◽  
Average Growth ◽  
Density Dependent ◽  
Dependent Growth

Abstract Quantifying the degree of density-dependence in stock–recruit relationships is critical to understanding fish population dynamics. The Shepherd and Cushing (1980) model couples a simple model of density-dependent larval growth with a constant rate of mortality to predict numbers surviving to recruitment. The model has not been evaluated using field data, nor have its predictions been compared with those from other models. Here, the S&C model, an individual-based model (IBM), and a regression model are applied to 8 years of field data for striped bass larvae in the Potomac River, Maryland, USA, to predict larval carrying capacity (K) and percentage of recruitment lost as a consequence of density-dependent growth. The IBM and the regression model were corroborated by comparing their predictions of average growth rates of larvae and relative recruitment strengths to observed values for the 8 years of field data. Although the IBM and the regression model differed in their predictions of several important intermediate variables, both models predicted higher values of K and lower values of density-dependent growth than did the S&C model. Over the 8 years, the IBM and the regression model predicted an average of 0.3 and 1.8% recruitment lost as a result of density-dependent growth, respectively. In contrast, the S&C model predicted much higher recruitment lost (average of 27%). Slight differences in the assumed rate of mortality used in the S&C model resulted in values of carrying capacity similar to those predicted by the IBM and the regression model. Difficulties in estimating parameters of the S&C model from field data are discussed.

Optimal Thinning of a Year-Class with Density-Dependent Growth

1986 ◽  
Vol 43 (4) ◽  
pp. 889-892 ◽  
Author(s):  
Rögnvaldur Hannesson
Keyword(s):  
Density Dependence ◽  
Optimal Harvesting ◽  
Early Date ◽  
Density Dependent ◽  
Moderate Density ◽  
Class A ◽  
Dependent Growth ◽  
The Impact ◽  
Harvesting Costs

I consider the impact of density-dependent growth on the optimal harvesting of a year-class of fish. In general, density dependence makes "thinning" of the year-class a desirable strategy. Moderate density dependence implies that thinning should be gradual, even in the case of zero harvesting costs where the optimal harvesting strategy would otherwise be instantaneous harvesting. Strong density dependence calls for an immediate thinning at an early date, in the case of zero harvesting costs.

scholarly journals Intra- and inter-specific density dependence of body condition, growth, and habitat temperature in chub mackerel (Scomber japonicus)

2021 ◽  
Author(s):  
Yasuhiro Kamimura ◽  
Makoto Taga ◽  
Ryuji Yukami ◽  
Chikako Watanabe ◽  
Sho Furuichi
Keyword(s):  
Density Dependence ◽  
Body Condition ◽  
Fish Population ◽  
Scomber Japonicus ◽  
Chub Mackerel ◽  
Negative Effects ◽  
Japanese Sardine ◽  
Habitat Temperature ◽  
Competition For Food ◽  
Temperature And Growth

The density dependence of growth and body condition have important impacts on fish population dynamics and fisheries management. Although population density is known to affect the temperature of the habitat selected, how this affects the density dependence of growth and body condition remains unclear. Here, we investigated annual changes in body condition, habitat temperature, and cohort-specific growth of chub mackerel (Scomber japonicus) in the western North Pacific and examined quarterly changes in the density dependence of body condition. We hypothesized that chub mackerel body condition is affected both directly (e.g., through competition for food) and indirectly (through changes in habitat temperature) by the abundance of both conspecifics (i.e., chub mackerel) and heterospecifics (the Japanese sardine Sardinops melanostictus). Indeed, chub mackerel body condition, habitat temperature, and growth all decreased with increasing conspecific and heterospecific abundance. Mean annual growth rates in chub mackerel were positively corelated with body condition. The best model showed that conspecific and/or heterospecific abundance had strong negative effects on chub mackerel body condition in all seasons, and influenced habitat temperature in some seasons. By contrast, temperature effects on body condition were weak. Therefore, direct effects likely have more impact than indirect effects on density-dependent body condition and growth.

scholarly journals Roles of density-dependent growth and life history evolution in accounting for fisheries-induced trait changes

2016 ◽  
Vol 113 (52) ◽  
pp. 15030-15035 ◽  
Author(s):  
Anne Maria Eikeset ◽  
Erin S. Dunlop ◽  
Mikko Heino ◽  
Geir Storvik ◽  
Nils C. Stenseth ◽  
...  
Keyword(s):  
Life History ◽  
Density Dependence ◽  
Time Series Data ◽  
Life History Evolution ◽  
Series Data ◽  
Ecological Processes ◽  
Arctic Cod ◽  
Density Dependent ◽  
History Evolution ◽  
Dependent Growth

The relative roles of density dependence and life history evolution in contributing to rapid fisheries-induced trait changes remain debated. In the 1930s, northeast Arctic cod (Gadus morhua), currently the world’s largest cod stock, experienced a shift from a traditional spawning-ground fishery to an industrial trawl fishery with elevated exploitation in the stock’s feeding grounds. Since then, age and length at maturation have declined dramatically, a trend paralleled in other exploited stocks worldwide. These trends can be explained by demographic truncation of the population’s age structure, phenotypic plasticity in maturation arising through density-dependent growth, fisheries-induced evolution favoring faster-growing or earlier-maturing fish, or a combination of these processes. Here, we use a multitrait eco-evolutionary model to assess the capacity of these processes to reproduce 74 y of historical data on age and length at maturation in northeast Arctic cod, while mimicking the stock’s historical harvesting regime. Our results show that model predictions critically depend on the assumed density dependence of growth: when this is weak, life history evolution might be necessary to prevent stock collapse, whereas when a stronger density dependence estimated from recent data is used, the role of evolution in explaining fisheries-induced trait changes is diminished. Our integrative analysis of density-dependent growth, multitrait evolution, and stock-specific time series data underscores the importance of jointly considering evolutionary and ecological processes, enabling a more comprehensive perspective on empirically observed stock dynamics than previous studies could provide.

scholarly journals Age and growth of redfish (Sebastes marinus, S. mentella, and S. fasciatus) on the Flemish Cap (Northwest Atlantic)

2004 ◽  
Vol 61 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Fran Saborido-Rey ◽  
Dolores Garabana ◽  
Santiago Cerviño
Keyword(s):  
Growth Rate ◽  
Density Dependence ◽  
Slow Rate ◽  
Age Determination ◽  
Age And Growth ◽  
Northwest Atlantic ◽  
Density Dependent ◽  
Dependent Growth ◽  
Sebastes Mentella

Abstract Age determination of redfish is difficult. In this paper, the ages of Sebastes mentella on the Flemish Cap are validated by following year classes from 1991 to 2000. The criteria used for S. mentella are consistent and coherent. The growth of different year classes is described and compared, and density-dependence is demonstrated to influence the growth rate of the strong 1990 year class, growth of that year class being the slowest of those followed. The slow rate of growth prevented that year class from maturing at the anticipated age. Growth is also compared between sexes, of S. mentella, S. marinus, and S. fasciatus, revealing that females grow faster than males. Finally, growth rate is compared among species. S. marinus grows fastest and S. mentella slowest, although the influence of density-dependent growth in S. mentella needs to be taken into consideration.

Impacts of climate change on growth, migration and recruitment success of Japanese sardine (Sardinops melanostictus) in the western North Pacific

2012 ◽  
Vol 115 (3-4) ◽  
pp. 485-503 ◽  
Author(s):  
Takeshi Okunishi ◽  
Shin-ichi Ito ◽  
Taketo Hashioka ◽  
Takashi T. Sakamoto ◽  
Naoki Yoshie ◽  
...  
Keyword(s):  
Climate Change ◽  
North Pacific ◽  
Western North Pacific ◽  
Japanese Sardine ◽  
Recruitment Success ◽  
Impacts Of Climate Change
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