Factors Affecting Catch‐and‐Release Mortality of Bluefish

Abstract

Abstract.-Recreational harvests of bluefish Pomatomus saltatrix along the U.S. coast from Maine to Florida exceed commercial harvests, and in recent years about 60-70% of angler-captured fish are released alive. The proportion of fish that survive hooking, handling, and release back to the ocean is unknown; however, if catch-and-release mortality is high, it may represent a significant component of the overall bluefish mortality rate. We estimated long-term (21-d) hooking mortality rates of field-captured bluefish and investigated the effects of various factors on postrelease mortality. Age, length, and the occurrence of bleeding were significant factors associated with catch-and-release mortality, which we estimated to be 38.8%. About 65% of the mortality was initial mortality, and the remainder was delayed mortality. We also performed a laboratory study to examine the physiological response of bluefish to two independent processes (hooking and release versus transfer in coolers to the laboratory) relevant to the field study. Laboratory-held fish that were hooked and released exhibited elevated concentrations of potassium in their blood, suggesting that they experienced either an osmotic imbalance or cellular damage. Laboratory-held fish exposed to the transfer treatment only exhibited osmotic imbalance (elevated plasma sodium concentration) and evidence of anaerobic metabolism (elevated plasma lactate concentration). Our findings indicate that bluefish age and size contribute to variable levels of metabolic stress and that delayed postrelease mortality is considerable.

Immediate fate of angled-and-released Australian bass Macquaria novemaculeata

“…Another limitation that may have underestimated the injuries and/or mortality of fish during this study was the short monitoring period. In other studies, initial mortality may account for the majority of fish deaths, but this may underestimate total mortality by not including delayed mortalities (Fabrizio et al, 2008); therefore, care needs to be taken when interpreting such results. However, the short monitoring period was chosen as a low-cost alternative to allow greater replication of monitoring across a range of tournaments.…”

Challenges in Assessing Fish Welfare

“…Anglers are less likely to catch a fi sh that they just caught and released than a fi sh that has never been caught (Askey et al 2006), suggesting that the fi sh was aware of the unpleasantness of the experience (i.e., in operational terms, a negative reward that reduces response frequency). Indeed, a recent study showed that catch and release practices impair fi sh welfare (Fabrizio et al 2008). …”

Catch-and-release angling mortality of south-eastern AustralianPomatomus saltatrix

“…While there is substantial interpopulation variation among biological traits (reflecting diverse environmental conditions), all stocks of P. saltatrix undertake fairly defined annual inshore spawning migrations (Juanes et al 1996). Such movements render them vulnerable to various inshore fisheries, including recreational hook and line off Australia (Ayvazian et al 2002), eastern USA (Fabrizio et al 2008) and southern Africa (Potts et al 2009). …”

“…Most stocks of P. saltatrix are considered fully-or overexploited (Ayvazian et al 2002, Leigh and O'Neill 2004, Fabrizio et al 2008. In an attempt to manage fishing mortality, and depending on stock-specific biological characteristics, recreational fishery regulations have included minimum legal sizes (typically between 23-35 cm TL), quotas (3-20 fish angler -1 day -1 ) and, for some populations, temporal closures to coincide with spawning aggregations (e.g.…”

“…In an attempt to manage fishing mortality, and depending on stock-specific biological characteristics, recreational fishery regulations have included minimum legal sizes (typically between 23-35 cm TL), quotas (3-20 fish angler -1 day -1 ) and, for some populations, temporal closures to coincide with spawning aggregations (e.g. Ward et al 2003, Fabrizio et al 2008). An inherent prerequisite of these management controls is that most angled-and-released P. saltatrix survive.…”