Dynamics of fisheries that affect the population growth rate coefficient

Jensen, A. L.

doi:10.1007/bf01866934

“…Equation (A.1.1) below is a modification of the original Euler-Lotka equation in which the integration is performed from age 0; when there is no reproduction in the age-0 class of individuals, the integration starting at age 1 is equivalent ). The initial guess for r in the calculation was 0.4, based on Jensen's (1984) surplus production model for Ciscoes in Lake Superior. The equation is where t denotes age, T is the maximum age of the species, l t denotes survivorship at age, and m t is the number of age-1 recruits expected to be produced by females of age t. For further details on the calculation of l t and m t , please see .…”

Section: Appendix 1: Specification Of Priorsmentioning

confidence: 99%

Temperature‐Driven Decline of a Cisco Population in Mille Lacs Lake, Minnesota

Kumar

¹

,

Martell

²

,

Pitcher

³

et al. 2013

N American J Fish Manag

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Mille Lacs Lake, Minnesota, has experienced a decline in the population of Cisco Coregonus artedi since the 1980s. Cisco is a coldwater stenotherm, and the population decline is often attributed to a general increase in the lake temperature. However, there also has been a fishery for this species during the last 20 years. To investigate the influence of temperature on this decline, three versions of a surplus production model (SPM) were formulated: (1) SPM with observation error only, (2) SPM with observation error and a maximum temperature anomaly, and (3) state‐space SPM with a maximum temperature anomaly and random effects process error. Data on CPUE of sampling gill nets from 1985 to 2007 were used as an index of fish abundance for the lake population. The model parameters were estimated by fitting the predicted CPUE to the observed CPUE. The analysis indicated that temperature explained 36% (model 2) and 40% (model 3) of the change in Cisco abundance. Temperature‐influenced, time‐varying carrying capacity and maximum sustainable yield (MSY) were also estimated. We concluded that the causes of Cisco decline were a combination of temperature and fishing pressure. Received April 26, 2012; accepted March 12, 2013

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“…Natural mortality rates can be density dependent, often due to limited refuge availability as well as predator functional responses (Anderson 2001). Additionally, certain populations are subject to mortality by fishing which can affect age-structures and abundance, impacting the growth of populations (Jensen 1984).…”

Section: Introductionmentioning

confidence: 99%

The consequences of complex habitat loss for the New Zealand blue cod, Parapercis colias

Wade¹

0

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<p>Climate driven threats are predicted to decrease the complexity of biogenic habitats. Within temperate coastal marine environments, we know that complex macroalgal beds support more complex communities through the provision of microhabitats and refuges. Macroalgal habitats have potential interacting benefits and costs for predators, as increased macroalgal biomass supports higher richness and diversity of prey species, but prey within these habitats might be more difficult to catch. An important New Zealand fishery species, the blue cod (Parapercis colias), is a large bodied temperate reef fish found exclusively throughout the coastal waters of New Zealand. Its dependence on subtidal coastal reef environments mean that it is important to understand how a loss of complex macroalgal habitats might alter the way that blue cod forage, and how the trade-off between prey abundance and availability will affect its abundance and productivity. This thesis aims to understand the influence of complex macroalgal habitats on P. colias prey availability and behaviour, on the foraging success of P. colias, and ultimately on P. colias population dynamics. Experiments were conducted using choice chambers to evaluate whether two alternate P. colias prey, Forsterygion lapillum and Heterozius rotundifrons, showed a preference for complex habitats with and without predation risk. Both species preferred complex habitats in the absence of predation cues, but F. lapillum showed a more consistent preference for complexity in response to predation risk. A mesocosm experiment was used to investigate whether the consumption rate and functional response of P. colias differs for these two prey types in the presence and absence of habitat complexity. Results indicated that the mobile fish prey, F. lapillum benefitted from the refuges provided by complexity and suffered lower consumption rates, whereas the sedentary crab, H. rotundifrons did not. Finally, using a simple population model, the trade-off between prey abundance and predation success on the population dynamics of P. colias with and without habitat complexity was explored. Models showed that scenarios with complex macroalgal habitats generally support more predators, and faster population growth rates than scenarios lacking habitat complexity. However, scenarios with complex habitats were predicted to be more sensitive to fishing pressure and have the potential to be more vulnerable to overexploitation. These results highlight the importance of understanding how habitat complexity mediates relationships between commercially important fishery species and their prey, in order to understand how habitat loss may alter their foraging success and population dynamics.</p>

show abstract

“…Natural mortality rates can be density dependent, often due to limited refuge availability as well as predator functional responses (Anderson 2001). Additionally, certain populations are subject to mortality by fishing which can affect age-structures and abundance, impacting the growth of populations (Jensen 1984).…”

Section: Introductionmentioning

confidence: 99%

The consequences of complex habitat loss for the New Zealand blue cod, Parapercis colias

Wade¹

0

View full text Add to dashboard Cite

<p>Climate driven threats are predicted to decrease the complexity of biogenic habitats. Within temperate coastal marine environments, we know that complex macroalgal beds support more complex communities through the provision of microhabitats and refuges. Macroalgal habitats have potential interacting benefits and costs for predators, as increased macroalgal biomass supports higher richness and diversity of prey species, but prey within these habitats might be more difficult to catch. An important New Zealand fishery species, the blue cod (Parapercis colias), is a large bodied temperate reef fish found exclusively throughout the coastal waters of New Zealand. Its dependence on subtidal coastal reef environments mean that it is important to understand how a loss of complex macroalgal habitats might alter the way that blue cod forage, and how the trade-off between prey abundance and availability will affect its abundance and productivity. This thesis aims to understand the influence of complex macroalgal habitats on P. colias prey availability and behaviour, on the foraging success of P. colias, and ultimately on P. colias population dynamics. Experiments were conducted using choice chambers to evaluate whether two alternate P. colias prey, Forsterygion lapillum and Heterozius rotundifrons, showed a preference for complex habitats with and without predation risk. Both species preferred complex habitats in the absence of predation cues, but F. lapillum showed a more consistent preference for complexity in response to predation risk. A mesocosm experiment was used to investigate whether the consumption rate and functional response of P. colias differs for these two prey types in the presence and absence of habitat complexity. Results indicated that the mobile fish prey, F. lapillum benefitted from the refuges provided by complexity and suffered lower consumption rates, whereas the sedentary crab, H. rotundifrons did not. Finally, using a simple population model, the trade-off between prey abundance and predation success on the population dynamics of P. colias with and without habitat complexity was explored. Models showed that scenarios with complex macroalgal habitats generally support more predators, and faster population growth rates than scenarios lacking habitat complexity. However, scenarios with complex habitats were predicted to be more sensitive to fishing pressure and have the potential to be more vulnerable to overexploitation. These results highlight the importance of understanding how habitat complexity mediates relationships between commercially important fishery species and their prey, in order to understand how habitat loss may alter their foraging success and population dynamics.</p>

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Dynamics of fisheries that affect the population growth rate coefficient

Cited by 3 publications

References 12 publications

Temperature‐Driven Decline of a Cisco Population in Mille Lacs Lake, Minnesota

Temperature‐Driven Decline of a Cisco Population in Mille Lacs Lake, Minnesota

The consequences of complex habitat loss for the New Zealand blue cod, Parapercis colias

The consequences of complex habitat loss for the New Zealand blue cod, Parapercis colias

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