Mortality Rate of Fishes in the Pelagic Ecosystem

Peterson, Ingrid; Wroblewski, Joe

doi:10.1139/f84-131

Cited by 439 publications

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“…Age-independent mortality estimates were almost identical for males and females. Age-specific mortality estimates from the Peterson & Wroblewski (1984) method declined from 0.21 yr -1 for newborn individuals to 0.09 yr -1 at maximum age (32 yr), overlapping the range identified by the age-independent methods.…”

Section: Resultsmentioning

confidence: 50%

“…Natural mortality was estimated using a range of indirect techniques based on life-history data to provide a comparison with those estimated from telemetry data. Six estimators of constant lifetime mortality (Pauly 1980, Hoenig 1983, Jensen 1996 and one method of age-specific mortality (Peterson & Wroblewski 1984) were used. All life-history data were taken from Wintner et al (2002) and Dudley & Simpfendorfer (2006).…”

Section: Methodsmentioning

confidence: 99%

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Estuarine nursery areas provide a low-mortality environment for young bull sharks Carcharhinus leucas

Heupel¹,

Simpfendorfer²

2011

Mar. Ecol. Prog. Ser.

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Defining the role and impact of mortality within aquatic populations is often difficult. As a result, we still lack a clear understanding of the level of mortality in natural populations and the role habitat may play in survival. We used long-term acoustic monitoring of neonate bull sharks Carcharhinus leucas in a south Florida estuary to determine mortality rates within this population. Estimates of natural, fishing and total mortality varied among the years examined, but not significantly, suggesting similar survival among years with the majority of individuals (77%) surviving beyond 18 mo. Compared with other juvenile sharks, mortality rates of C. leucas were low. The results indicate that the use of mesohaline estuarine habitats by C. leucas may provide benefits that are not present in more marine habitats where their counterparts reside. Use of estuarine regions may be a successful ecological strategy for improving survival because of reduced predation and competition.

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Section: Resultsmentioning

confidence: 50%

Section: Methodsmentioning

confidence: 99%

Estuarine nursery areas provide a low-mortality environment for young bull sharks Carcharhinus leucas

Heupel¹,

Simpfendorfer²

2011

Mar. Ecol. Prog. Ser.

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“…Methods 5 and 6 produced similar ranges of estimates, roughly in the middle of the collective range. Estimates from method 8, based on weight, were similar to those from method 3 and were nearly identical to estimates based on the more theoretical approach of Peterson and Wroblewski (1984). Although we did not include their approach in Table 1, it would add weight to M estimates in the range of 0.5-1.2 per year.…”

Section: Indirect Estimatesmentioning

confidence: 67%

“…This method allows M to vary among individuals; however, we used it with a range of sizes for exploitable blue crabs (.76 mm CW) to produce a range of M estimates in a way similar to the other methods. Peterson and Wroblewski (1984) concluded that mortality due to predation in pelagic marine ecosystems was a power function of body weight. Lorenzen (1996) related estimates of M to wet body weight for a large and diverse data set for fishes of all sizes in natural ecosystems (lakes, rivers, marine systems) and also found that M was a power function of body weight.…”

Section: Methodsmentioning

confidence: 99%

Direct and Indirect Estimates of Natural Mortality for Chesapeake Bay Blue Crab

et al. 2007

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Abstract.-Analyses of the population dynamics of blue crab Callinectes sapidus have been complicated by a lack of estimates of the instantaneous natural mortality rate (M). We developed the first direct estimates of M for this species by solving Baranov's catch equation for M given estimates of annual survival rate and exploitation rate. Annual survival rates were estimated from a tagging study on adult female blue crabs in Chesapeake Bay, and female-specific exploitation rates for the same stock were estimated by comparing commercial catches with abundances estimated from a dredge survey. We also used eight published methods Our results indicate that natural mortality of blue crab is higher than previously believed, and we consider M values between 0.7 and 1.1 per year to be reasonable for the exploitable stock in Chesapeake Bay. Remaining uncertainty about M makes it necessary to evaluate a range of estimates in assessment models.The estimation of natural mortality rates is one of the most difficult and most critical elements of many fishery stock assessments. The natural mortality rate is a key determinant of the potential productivity of a stock and thus the amount of exploitation a stock can sustain. In general, assuming that natural mortality and harvest mortality are additive, stocks with higher natural mortality rates are more productive and are able to sustain higher rates of exploitation. Lacking evidence to the contrary, most stock assessments assume that natural mortality is constant through time as well as across the sizes or ages of the exploited animals. Thus, a single estimate of the instantaneous natural mortality rate (M) is presumed to apply to the entire exploitable stock.The values used for M in assessment models can have substantial effects on model results, biological conclusions, and management recommendations. For a simple age-structured model, Clark (1999) found that stock abundance and target harvest rates could be severely overestimated when M was overestimated by as little as 0.1 per year or less, especially when fishing mortality was low (F , 0.3 per year). Similarly, harvest policies for U.S. West Coast groundfish based on a catch-at-age model were sensitive to changes in M of less than 0.05 per year (Williams 2002). Using a length-structured model for red king crab Paralithodes camtschaticus in Bristol Bay, Alaska, Zheng et al. (1997a, 1997b found that stock rebuilding and longterm harvest strategies were highly sensitive to changes in M of 0.2-0.3 per year. These and other results indicate that it is desirable to have precise knowledge about M for assessment purposes.Unfortunately, estimates of M used in stock assessment models are often uncertain, partly because it is difficult and expensive to estimate the parameter. In practice, values of M for use in stock assessments are obtained by two types of methods, which we refer to as direct and indirect. Direct methods involve estimating M from data pertaining solely to the species or stock of interest. Direct methods include field ...

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“…Here, the high asset values (e.g. large energy reserves or body size) lead to higher competitive ability, and reduce risks due to predator gape-limits or increased vigor (Mittelbach 1981;Peterson and Wroblewski 1984;Werner and Gilliam 1984;Travis et al 1985; but see Lima 1986). The influence of these feedback systems could differ in strength in different environmental contexts (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Supplemental Information 1: Supplementary Material

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PrePrintsAbstract Animals generally adjust their behavior in response to bodily state (e.g. size and energy reserves) to optimize energy intake in relation to mortality risk, weighing predation probability against starvation. Here we investigated whether brown trout adjust their behavior in relation to feeding history (energetic status) and body size during a major early-life selection bottleneck, when fast growth also appear to be important. We manipulated growth using different food ration schemes over two consecutive time periods (P1 = 12 days, P2 = 23 days), excluding social effects through individual isolation. During these experimental periods the fish were fed either high or low food rations in a crossed design. In behavioral trials following the treatment, where acute hunger levels were standardized among all treatments, fish that were initially fed high rations (P1) and thereafter low rations (P2) had on average 15-21% higher swimming activity than the other groups, but large within-treatment variation rendered only weak statistical support for the effect. Furthermore, fish on low ration during P2 tended to be more aggressive than fish on high ration. Size was related to behavioral expression, with larger fish being more active and aggressive. Swimming activity and active aggression were positively correlated, forming a behavioral syndrome in the studied population. Based on these behavioral traits we could also distinguish two behavioral clusters, one consisting of more active and aggressive individuals, and the other consisting of less active and aggressive individuals. This indicates that two behavioral strategies may exist in young brown trout.

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Mortality Rate of Fishes in the Pelagic Ecosystem

Cited by 439 publications

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Estuarine nursery areas provide a low-mortality environment for young bull sharks Carcharhinus leucas

Estuarine nursery areas provide a low-mortality environment for young bull sharks Carcharhinus leucas

Direct and Indirect Estimates of Natural Mortality for Chesapeake Bay Blue Crab

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