Gear-Related Mortality in Selective Fisheries for Ocean Salmon

Lawson, Peter W.; Sampson, David B.

doi:10.1577/1548-8675(1996)016<0512:grmisf>2.3.co;2

Cited by 17 publications

(26 citation statements)

References 7 publications

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“…As has been previously demonstrated by Lawson and Sampson (1996) and Yuen and Conrad (2011), for a fixed set of release mortality rates, relative bias in the calculation of total exploitation rate on the unmarked cohort increases as the exploitation rate increases on the marked cohort ( Figure 3). The effect of increasing the proportion of the total exploitation rate on the marked cohort in MSF is seen by comparing Figures 3A, 3B, and 3C.…”

Section: Estimation Of Total Exploitation Rate For the Unmarked Cohortsupporting

confidence: 73%

“…For one listed stock, fisheries were structured to fish up to the exploitation rate guideline; thus, after accounting for bias the exploitation rate for this stock exceeded the guideline in both years (Conrad and Hagen-Breaux 2011 Several current salmon fishery management models, used for both preseason planning and postseason assessment of fisheries, calculate mortalities for unmarked cohorts in MSF using methods that rely on a linear relationship between a base period exploitation rate (μ Base ) and a release-mortality rate. Previous research has demonstrated that the single-pool paradigm that most of these models rely on results in an underestimate of the unmarked mortalities occurring in MSF (Lawson and Sampson 1996) and any concurrent NSF (Yuen and Conrad 2011). We have proposed methods that correct for this bias and demonstrated through simulation that they provide unbiased calculations of the unmarked mortalities in both MSF and NSF.…”

Section: Discussionmentioning

confidence: 99%

“…Following the notation of Lawson and Sampson (1996), but with separate mark-recognition rates for marked (γ) and unmarked (ζ) fish and setting the parameters related to drop-off mortality to zero, the probability of a marked fish dying ( p M ) in a mark-selective fishery during time span t is…”

Section: Methodsmentioning

confidence: 99%

“…Lawson and Sampson (1996) demonstrated that in a markselective fishery, the actual mortality rate for unmarked fish is an increasing function of the time-period-specific exploitation rate. This causes the total number of unmarked mortalities in MSF to be underestimated by models relying on the linear relationship between exploitation rate and release-mortality rate.…”

mentioning

confidence: 99%

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Unbiased Methods for Calculating Mortality in Mark‐Selective Fisheries Models for Ocean Salmon

Conrad

Hagen-Breaux

Yuen

2013

N American J Fish Manag

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Mark‐selective fisheries (MSF) are increasingly being used as a strategy for managing fisheries for Coho Salmon Oncorhynchus kisutch and Chinook Salmon O. tshawytscha on the west coast of North America. Mark‐selective fisheries allow anglers to keep legal‐size Coho Salmon or Chinook Salmon with a missing adipose fin (typically hatchery fish) and require the release of those with an adipose fin (unmarked fish, which are usually wild fish). The objective of MSF is to provide meaningful fisheries on abundant stocks of hatchery salmon while reducing the impact on wild (unmarked) salmon stocks. As has been previously shown, the model currently used in the Pacific Fishery Management Council's preseason planning process to project mortalities for proposed Coho Salmon and Chinook Salmon fisheries underestimates the number of unmarked salmon mortalities occurring in MSF and concurrent nonselective fisheries. We propose equations that provide unbiased estimates of salmon mortalities that occur in these fisheries due to the release of fish. The performance of the proposed methods is evaluated and compared to the current methods using a simulation model. The methods are shown to provide unbiased calculations of total mortalities for unmarked salmon in both mark‐selective and concurrent nonselective fisheries. The unbiased methods are able to incorporate different release‐mortality and mark‐recognition rates for the fisheries modeled.Received July 24, 2012; accepted November 26, 2012

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Section: Estimation Of Total Exploitation Rate For the Unmarked Cohortsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Unbiased Methods for Calculating Mortality in Mark‐Selective Fisheries Models for Ocean Salmon

Conrad

Hagen-Breaux

Yuen

2013

N American J Fish Manag

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“…Lawson and Sampson (1996) developed a model that suggests in the overall mortality, drop-off mortality could be as important as hook-and-release mortality. Measuring this type of mortality is challenging.…”

Section: Mortalitymentioning

confidence: 99%

Animal welfare perspectives on recreational angling

Cooke

Sneddon

2007

Applied Animal Behaviour Science

134

127

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Fish captured by recreational anglers are often released either voluntarily or because of harvest regulations in a process called ''catch-and-release''. Catch-and-release angling is thought to be beneficial for the conservation of fish stocks based on the premise that most of the fish that are released survive. However, expanding interest in animal welfare has promoted debate regarding the ethics of catch-and-release angling. There is a growing recognition that fish can consciously experience nociception and that they have some capacity to experience pain and fear. Indeed, empirical anatomical, physiological, and behavioural evidence supports the notion that fish could experience these two forms of suffering (i.e., pain and fear). Based on that premise, we examine existing catch-and-release research from a welfare perspective to determine the extent to which potential pain and suffering could be caused. There are numerous studies that provide analyses of the consequences of catch-and-release on the individual demonstrating physical injury, sublethal alterations in behaviour, physiology, or fitness, and mortality. Collectively, this research suggests that all recreational fishing results in some level of injury and stress to an individual fish. However, the severity of injury, magnitude of stress, and potential for mortality varies extensively in response to a variety of factors. Interestingly, this information can be used to identify strategies that anglers may adopt that minimize these effects through changes in either gear (e.g., type of hook, bait, or net) or angling practices (e.g., duration of fight and air exposure, fishing during extreme environmental conditions, fishing during the reproductive period). Although aspects of the catch-and-release angling experience cannot be refined (e.g., the need to physically hook the fish), we argue that informed anglers and fisheries managers can adopt practices to improve the welfare of angled fish. Although consideration of fish welfare is somewhat abstract to most anglers and fisheries managers, ultimately it benefits the individual fish, while simultaneously benefiting the fish population and fishery. Greater integration of welfare consideration into recreational and commercial fisheries should promote innovative solutions to minimize pain and suffering, which should also enhance conservation and management. #

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