Hooking Mortality Research Articles

Factors influencing the at‐haulback mortality of striped marlin Tetrapturus audax caught by tuna longline fishery in the western Indian Ocean

Abstract Striped marlin (Tetrapturus audax) is an oceanic pelagic migratory fish. The stock status of striped marlin in the Indian Ocean is now considered to be overfished and subject to overfishing. Quantifying the level of at‐haulback mortality caused by longline fisheries for tuna and tuna‐like species is critical to reducing fishing pressure and protecting the fate of billfish stocks. This study was based on data from 2482 longline fishing operations recorded by Chinese observers in the western Indian Ocean from 2012 to 2019. The dataset includes information on the survival status of 774 striped marlin and their corresponding details. We used a generalized linear model (GLM) to analyse the level of at‐haulback mortality and its potential influencing factors. The results indicate that the distribution of 774 striped marlin had a lower jaw‐fork length (LJFL) range from 130 to 220 cm, and 51.5% of the specimens died at the time of haul‐back. The GLM model revealed that quarter, sea‐surface temperature (SST), hook type, LJFL, chlorophyll (CHL) and longitude had significant effects on at‐haulback condition when the fish were retrieved on board, with the quarter and sea surface temperature having the most significant effects. The interaction term between hook type and LJFL also had a significant effect on at‐haulback mortality, with the model predictions showing that mortality increased with LJFL when using circle hooks but decreased when using Japanese tuna hooks. There has been limited observational analysis of hooking mortality rates for striped marlin, and the present study may provide an important reference for the conservation and management of striped marlin stocks in the Indian Ocean.

Effects of capture depth on walleye hooking mortality during ice fishing

Lyon CA, Davis JL, Fincel MJ, Chipps SR. 2022. Effects of capture depth on walleye hooking mortality during ice fishing. Lake Reserv Manage. XX:XXX–XXX. Length-based regulations are a common tool used to limit fishing mortality by controlling the size of fish harvested. While such regulations are helpful in managing fish populations, mortality associated with catch-and-release fishing may negatively impact a fishery. We evaluated factors affecting hooking mortality of walleye (Sander vitreus) in 2 mainstem Missouri River reservoirs in South Dakota. Winter walleye hooking mortality was evaluated during the ice fishing season in February and March 2020. After capture, walleye (n = 55) were placed into holding pens for 12 to 72 h to monitor postrelease mortality. Hooking mortality was found to be 20% following angling. Capture depth, landing time, and time in pen were the most influential variables on probability of hooking mortality (pm ). We observed a sharp increase in pm for walleye captured at depths from 10 to 12 m, where the probability of mortality for fish increased appreciably from 5 to 37%, respectively. Our findings indicate that hooking mortality during the ice fishing season can be substantial in lakes where walleye angling occurs at depths greater than 10 m.

Does catch-and-release angling pose a threat to American eel? A hooking mortality experiment

Does catch-and-release angling pose a threat to American eel? A hooking mortality experiment

Catch-and-Release Ice Fishing with a Mormyshka for Roach (Rutilus rutilus) and European Perch (Perca fluviatilis)

Abstract This study examined and described the basic parameters of the catch-and-release angling of roach Rutilus rutilus and European perch Perca fluviatilis with the mormyshka technique. Catch efficiency, the size of the fish caught, the time required to unhook the fish and the total time during which the fish were handled, hooking location, the occurrence of injury and initial hooking mortality were determined. The study indicates that the mormyshka technique is an effective way to catch roach and European perch when ice fishing. The efficiency of the catches and landings was similar for barbed and barbless hooks. The mormyshka technique also proved to be safe for the fish during catch-and-release fishing. The decided majority of fish were hooked shallowly on the upper jaw, which is a safe location, and injury occurred rarely regardless of the hook type. Generally unhooking the fish from the mormyshka hook was seamless and fish handling was brief. Additionally, when roach were caught with barbless hooks, unhooking time and handling was shorter than it was with barbed hooks. No initial hooking mortality was observed in roach, while it occurred in only two specimens of European perch.

Optimal harvest regulations under conflicting tradeoffs between conservation and recreational fishery objectives

Length-based harvest regulations alter the fishing-induced demographic and evolutionary trajectories of exploited stocks and thus shape the existing tradeoffs among fishery and conservation objectives. We used a structurally realistic eco-genetic individual-based harvest model that implements dynamic angling mortality and cryptic mortality sources (illegal harvest and hooking mortality). We (1) analyzed the effects of alternative length-based harvest regulations under scenarios involving different combinations of exploitation intensity and hooking mortality on a suite of indicators of fishery performance and conservation status of a freshwater fish stock, and (2) determined the regulations that optimize the tradeoff among selected indicators under different management strategies, and fishery and conservation objectives. Fishing scenarios under a maximum-length limit regulation maximized harvest yield but led always to recruitment overfishing, irrespective of the exploitation and hooking mortality rates simulated. Fishing scenarios under a harvest slot limits regulation (HS) were best at maintaining a high status of old, large, fecund fish and a more natural age-structure with higher biomass and reproductive potential, performing increasingly better than minimum-length limit (MLL) regulations with decreasing hooking mortality. Both regulation types were effective at preventing overexploitation and only under scenarios with low restrictiveness and high exploitation intensity and hooking mortality was the stock at risk of recruitment overfishing. MLLs outperformed HS regulations in terms of fishery performance, consistently presenting greater harvest yield and efficiency, and size of harvested fish. High rates of hooking mortality rendered HS regulations less effective than assumed, so they were always outperformed by MLLs irrespective of the management strategy and objectives. When hooking mortality was low, HSs constituted the optimal regulation type in most cases except when high fishery performance was favoured over conservation objectives or harvest of large fish was regarded as critically important.

Hooking mortality of swordfish in pelagic longlines: comments on the efficiency of minimum retention sizes

This paper revises detailed data on hooking (at-haulback) mortality of swordfish captured and discarded by pelagic longlines, using as a case study the shallow night setting Portuguese pelagic longline fishery that targets manly swordfish, in the Atlantic Ocean. The overall at-haulback mortality for swordfish was very high, specifically 85.2% for all sample/sizes combined, and even higher for the smaller sizes classes. Specifically, observed at-haulback mortality was 87.8% for specimens smaller than 125 cm lower jaw fork length (LJFL) and 88.1% for specimens smaller than 119 cm LJFL, corresponding to the minimum landing size options currently in place in the Atlantic Ocean. The mortality was modeled with logistic generalized linear models, showing that specimen size, sea surface temperature (SST) and mode of operation were significant variables, and with the hooking mortality decreasing with specimen size while increasing with SST. Even though this study only focuses one fishery, the data is widespread and covers a wide Atlantic area, being representative of most modern shallow setting longlines targeting swordfish, and including both fresh and freezer operating vessels. Additionally, this study only focuses hooking mortality, with a note that the overall mortality rates are likely higher due to post-release mortality of released specimens. Overall, this work presents new and important information on swordfish mortality and opens the discussion on the efficiency of the minimum landing sizes for swordfish currently in place in the Atlantic that were established mainly to protect juvenile swordfish.

Experimental assessment of circle vs. J hook performance and selectivity in the northern Gulf of Mexico recreational reef fish fishery

Few data exist to evaluate the performance or assess the potential impacts of hook regulations on catchability or selectivity of recreational fisheries in the northern Gulf of Mexico. The purpose of this study was to test the effects of hook type (circle vs. J hook) and hook size (1/0, 4/0, and 7/0) on catch composition, traumatic hooking, species-specific catches, and size-selectivity of red snapper, Lutjanus campechanus, and grey triggerfish, Balistes capriscus. Selectivity was estimated by conditioning size distributions from hook-specific catches against in situ size distributions observed with a remotely operated vehicle. Deep hooking (hook set in gills or beyond) was low in all hook treatments for red snapper (<10%) and grey triggerfish (<6%), but was generally higher with J hooks, especially for other fishes caught with the largest J hook (34%). Hook type did not significantly affect catches, but catches decreased significantly with increasing hook size in all groups except red snapper. Selectivity curves were dome-shaped for both focus species in all hook treatments and selection peaks were similar among treatments for red snapper. Peak selectivity was 78.1 mm larger for J hooks than circle hooks for grey triggerfish. Overall, study results indicate that the circle hook regulation may have reduced traumatic hooking mortality by up to 50%, and that catchability is similar between hook types for both red snapper and grey triggerfish when controlling for hook size. Strong dome-shaped selection estimated for nearly all selectivity curves suggest logistic size-selectivity assumptions in assessment models are likely inappropriate for recreational sectors targeting red snapper or grey triggerfish.

Characterizing loggerhead sea turtle, <I>Caretta caretta</I>, bycatch in the US shark bottom longline fishery

Sea turtle bycatch in longline fishing gear is an ongoing threat to the recovery of sea turtle populations. While considerable research has focused on pelagic longline fisheries, very little attention has been paid to captures of sea turtles in bottom longlines. Estimates of sea turtle takes in the shark bottom longline fishery have raised concern that this fishery may be impacting loggerhead sea turtle, Caretta caretta (Linnaeus, 1758), populations. However, there are no current management actions designed to reduce the bycatch of sea turtles in fisheries that target sharks using bottom longline gear because no studies have identified which factors, if any, influence the capture of a loggerhead sea turtle. We used generalized linear models to determine which factors influence the probability of loggerhead sea turtle captures in the shark bottom longline fishery, and which factors are related to at-vessel mortality. While a variety of fishing techniques were considered as factors, no particular fishing method was found to predict a capture of a sea turtle. The most significant factor in predicting the capture of a loggerhead sea turtle in shark bottom longline gear was the area fished. Soak time was found to predict at-vessel hooking mortality with the median time for a mortality to occur was 14–15 hrs. While no definitive fishing factor was identified in the capture or mortality of a loggerhead sea turtle, research is needed using controlled methods for further examining the factors affecting captures of sea turtles in this and other bottom longline fisheries.

Discards, hooking, and post-release mortality of porbeagle (Lamna nasus), shortfin mako (Isurus oxyrinchus), and blue shark (Prionace glauca) in the Canadian pelagic longline fishery

Discards, hooking, and post-release mortality of porbeagle (<i>Lamna nasus</i>), shortfin mako (<i>Isurus oxyrinchus</i>), and blue shark (<i>Prionace glauca</i>) in the Canadian pelagic longline fishery

Optimal management of recreational fisheries in the presence of hooking mortality and noncompliance — predictions from a bioeconomic model incorporating a mechanistic model of angler behavior

Using a bioeconomic model, we systematically investigated how hooking mortality and regulatory noncompliance influenced management outcomes across a range of freshwater fish species exploited by diverse angler populations. The model integrated an empirically based submodel describing the behaviour of three angler types with an age-structured fish population submodel calibrated to five life-history types (LHTs). Increased hooking mortality generally undermined regulation effectiveness, decreased socially optimal input (license numbers) and output regulations (minimum-size limits), and eroded the social welfare anglers derived from the fishery. However, the results strongly varied with LHT and angler type. Noncompliance had an isolated effect, primarily affecting fish species with low compensatory reserves when hooking mortality was low. However, in the absence of regulatory constraints on effort, noncompliance facilitated recruitment overfishing and increased the minimum-size limit required to avoid it. Despite added mortality from hooking and noncompliance, the strong dependence of angler utility on catch rates usually meant socially optimal management safeguarded biological sustainability. Yet, ignoring hooking mortality and noncompliance when predicting optimal regulations often led to population collapse. To conclude, models designed to derive recommendations for recreational fisheries management must consider both hooking mortality and noncompliance. Otherwise, dissatisfied anglers or biologically overfished stocks are possible.

Hooking Mortality and Landing Success Using Baited Circle Hooks Compared to Conventional Hook Types for Stream-Dwelling Trout

We estimated hooking and landing success and relative hooking mortality for stream-dwelling trout caught with baited circle and J hooks, J hook dry flies, and treble hook spinners (all hooks barbed). Trout were caught, individually marked, and released for 69 days. Deep-hooking rate was higher for trout captured with baited J hooks (21%) than for spinners (5%), baited circle hooks (4%), and dry flies (1%). Relative mortality rate was higher for trout captured with baited J hooks (25%) and spinners (29%) than for trout captured with baited circle hooks (7%) and dry flies (4%). Deep-hooking was two and six times higher for baited J hooks than baited circle hooks for fish caught actively and passively , respectively. For baited circle hooks, deep-hooking was over three times greater when using an active fishing method (i.e., an active hookset) compared to passive fishing method (no hookset), which conflicts with manufacturer&s recommendations on how circle hooks should be fished. Hooking success (ratio of hook-ups to number of fish strikes) was about one-third lower for baited circle hooks fished both passively and actively compared to other hook types and fishing methods, except for passively-fished baited J hooks. Once hooked, landing success (ratio of fish landed to number of hook-ups) was relatively high for all hook types and fishing methods (range 68–87%). Our results suggest that when bait fishing for trout in streams, circle hook use may reduce deep-hooking and hooking mortality (but also catch rate) regardless of whether anglers fish passively or actively.

Delayed Hooking Mortality of Blue Catfish Caught on Juglines

AbstractGrowing interest in catfish angling, particularly for trophy‐sized fish, has resulted in new regulations that limit the harvest of large Blue Catfish Ictalurus furcatus in several states. For these regulations to be effective, released fish must survive to further contribute to the fishery, either through reproduction or subsequent recapture. We investigated the effect of capture depth, hook type, water temperature, and fish size on the delayed hooking mortality of Blue Catfish caught on juglines. Blue Catfish (N = 559) were caught from three Oklahoma reservoirs with either 5/0 circle hooks or J‐hooks fished for 24‐h sets. One experimental fish (captured via jugline) and one control fish (captured via low‐frequency electrofishing) were then placed in field enclosures (N = 25) and monitored for mortality after 72 h. Mean mortality was low at 8.50% (range, 0.00–37.50%; SE, 1.81%). Mortality decreased significantly with decreasing water temperatures (P &lt; 0.01; odds ratio 1.1). Mortality was highest (mean = 25.31%) at water temperatures &gt;20°C and decreased to 3.89% in water temperatures &lt;20°C. We observed 0% mortality in water temperatures &lt;14°C. Hook type did not significantly affect mortality, nor did the depth in the water column where the fish was hooked. For every 100‐mm increase in total length, fish were six times less likely to die (odds ratio 0.17). Mean mortality for preferred‐size fish was low at 2.50%, and no mortalities were observed for memorable or trophy‐size fish. These results suggest that length regulations limiting the harvest of preferred‐size or larger fish should be effective as a large proportion of released fish should survive to further contribute to the fishery.Received July 23, 2012; accepted November 28, 2012

An overview of the hooking mortality of elasmobranchs caught in a swordfish pelagic longline fishery in the Atlantic Ocean

Hooking (or at-haulback) fishing mortality was analysed in elasmobranchs captured by Portuguese long- liners targeting swordfish in the Atlantic Ocean. Information was collected by on-board fishery observers who moni- tored 834 longline fishing sets between August 2008 and December 2011, and recorded information on 36 067 elasmo- branch specimens from 21 different taxa. The hooking mortality proportions were species-specific, with some species having relatively high percentages of live specimens at time of haulback (e.g., blue shark, crocodile shark, pelagic stingray, manta, devil and eagle rays), while others had higher percentages of dead specimens (e.g., smooth hammer- head, silky shark, bigeye thresher). For the most captured species (Prionace glauca, Pseudocarcharias kamoharai, Isurus oxyrinchus and Alopias superciliosus), logistic generalized linear models (GLMs) were carried out to compare the mortality rates between sexes, specimen sizes and the regions of operation of the fleet. The sex-specific proportions of hooking mortality were significantly different for blue and crocodile sharks, with the males of both species having higher proportions of hooking mortality than the females. Specimen size was significant for predicting the hooking mortality for blue and shortfin mako sharks: in both cases, the larger specimens had lower odds of dying due to the fishing process. There were differences in the hooking mortality depending on the region of operation of the fleet, but those differences were also species-specific. For blue and crocodile sharks, the hooking mortality was higher in the Equatorial and southern Atlantic areas (when compared to the NE Atlantic region), while the opposite was observed for the shortfin mako, with lower mortality rates in the NE tropical area compared with the other regions. The results presented in this paper can be integrated into future ecological risk assessment analysis for pelagic elasmobranchs. Fur- thermore, the new information can be used to evaluate the impact of recent recommendations prohibiting the retention of some vulnerable elasmobranch species.

Mortality of Walleyes Angled from the Deep Waters of Rainy Lake, Minnesota

AbstractExisting models of hooking mortality for walleyes Sander vitreus in large polymictic lakes are inadequate for estimating the number of catch‐and‐release mortalities in deeper, stratified lakes where fish are predominantly caught from depths greater than 10 m. To improve the understanding of how water depth affects catch‐and‐release mortality, logistic regression was used to investigate how depth of capture, fish length, and epilimnetic water temperature affect hooking mortality rates. In 2006 and 2007, 319 walleyes were caught by anglers at 5.8–17.1‐m depths during a total of 10 angling events (July–September) on Rainy Lake, Minnesota. Fish were released into holding cages that allowed them the opportunity to reestablish themselves at their depths of capture; survival was recorded after 5 d (2 d for one cage). After accounting for the effects of experimental handling time (i.e., the time between hook removal and fish placement in the holding cage), capture depth had the largest effect on mortality; increases in either factor were associated with higher mortality rates. A mixed‐effects model showed that pseudoreplication (i.e., correlations in survival rates among fish held in the same cage) did not detrimentally affect model parameter estimates or significance tests. In contrast to previous studies of hooking mortality in Minnesota, neither water temperature nor fish length best explained the mortality rates. By providing improvements over previous models, the logistic hooking mortality model developed in this study will allow managers to more effectively estimate hooking mortality rates in Rainy Lake and other deep lakes.Received February 11, 2011; accepted May 13, 2011

Winter Catch‐and‐Release Hooking Mortality of Saugers below Lock and Dam 3 of the Mississippi River

AbstractWe evaluated the effect of length and depth of capture of saugers Sander canadensis on winter hooking mortality below Lock and Dam 3 of the Mississippi River (i.e., Pool 4) by catching saugers using the most common recreational fishing gear in these fisheries (jig and plastic, jig and minnow, and jigging spoons) and holding the fish for 72 h in a net‐pen. Sauger winter hooking mortality was 26.4% and increased with depth of capture. Thirty‐three percent (56 of 172) of the saugers caught at depths of 9 to 24 m died, compared with only 2% (1 of 41) of those caught at depths of 9 m or less. There was no relationship between fish length and mortality; however, fish caught at depths of 12 m or less were significantly larger. We applied our hooking mortality estimates (26.4%) to a concurrent creel census and estimated that 2,500–2,900 kg of saugers were lost each year to winter hooking mortality. The percentage of total angling mortality (harvest and hooking) resulting from catch and release each winter was 30.5% (2,515 kg/8,256 kg) in 2005–2006 and 33.0% (2,812 kg/8,529 kg) in 2006–2007. Based on the historical abundance and annual mortality estimates available for Pool 4 saugers, winter hooking mortality did not substantially reduce the population. However, anglers may reduce winter catch‐and‐release hooking mortality by fishing in shallower water (&lt;9 m).Received May 12, 2010; accepted December 30, 2010

Relative Hooking Mortality among Walleyes Caught on Barbed and Barbless Octopus Hooks and Barbed Jigs

AbstractAnglers sometimes use alternatives or modifications to J‐shaped hooks to reduce hooking mortality in fish that are caught with live baits and then released. One such modification, the removal of barbs, has been evaluated for several fish species but has shown little promise for reducing hooking mortality; however, barbless hooks have not been evaluated for walleye Sander vitreus. We evaluated relative mortality for walleyes (228–419 mm total length) that were caught by means of bobber fishing with leeches on barbed (n = 179 fish) or barbless (n = 209) live‐bait octopus hooks or on barbed jigs (n = 193); after capture, the fish were held for 120 h in net pens. Holding mortality was a function of water temperature, cage density, bleeding level, and hook location; fish length and angler handling time did not significantly affect mortality. We combined hook location and bleeding level to create a single variable, hooking damage, which was used to replace the two variables in the initial model. This second model was similar to the first, indicating that hooking damage was correlated with mortality when controlling for the effects of water temperature and cage density. We also determined that hooking damage was correlated with hook type. For the 228–419‐mm walleyes in our study, barbed jigs caused less damage than live‐bait hooks and damage levels were similar between barbed and barbless live‐bait hooks. Given specified levels of hooking damage, holding mortality was independent of hook type. We hypothesize that the fish in this study were too small to swallow the jigs well and thus were hooked less critically and bled less than fish that were caught with live‐bait hooks. This study illustrates how gear type can affect hooking mortality based on the amount of damage caused when the fish is caught and adds to the body of literature indicating that the removal of barbs from hooks does not increase fish survival.Received March 15, 2010; accepted November 17, 2010

Assessing the Effects of Catch‐and‐Release Regulations on a Brook Trout Population Using an Age‐Structured Model

AbstractAs populations of wild brook trout Salvelinus fontinalis decline across the species' native range in North America, angling regulations such as fly‐fishing only and catch and release are being used by management agencies to conserve fish while maintaining angling opportunities. Postrelease (hooking) mortality may significantly shift the age structure and size structure of populations. To assess the possible influence of catch‐and‐release fishing on brook trout population structure, we applied data from several sources to build a deterministic population model that included age‐classes up to age 5. To assess the potential effect of fishing, we examined the changes in population density and age structure at varying levels of angler effort (0–400 angler‐hours·ha−1·year−1) and hooking mortality rates (0–14%). Assuming a low (5%) hooking mortality rate, trophy brook trout density (ages 4 and 5) decreased by 50% at an angling intensity of 160 angler‐hours·ha−1·year−1. As angling effort increased, the proportion of older fish (ages 3–5) declined further. At very high levels of angling effort (&gt;300 angler‐hours·ha−1·year−1), age‐4 and age‐5 fish were eliminated from the population. Increases in postrelease mortality rates resulted in similar declines for older age‐classes. The results of this simulation indicate that hooking mortality rates as might be common in catch‐and‐release fisheries may significantly shift the age structure of a population, thus reducing trophy angling potential.

Factors Influencing Short‐Term Hooking Mortality of Bluegills and the Implications for Restrictive Harvest Regulations

AbstractAngling can adversely affect populations of bluegill Lepomis macrochirus, and many state agencies have begun to explore restrictive creel and length limits. The fate of released fish can be influenced by a variety of factors, and the success of regulations could be reduced if the mortality of released bluegills is high. We conducted experiments using bluegills caught by the general angling public in Ridge Lake, Illinois, to quantify bluegill hooking mortality and test for the effects of bait type (live versus artificial), season (spring versus summer), retention time in live wells (1, 3, or 5 h), and retention gears (live wells versus fish baskets). Across all seasons and baits, the mortality of caught‐and‐released bluegills was low; the initial and short‐term mortality for fish immediately released was 4.4%. There were significant differences in hooking mortality with respect to bait type, retention gear, and retention time. Bluegills caught on live bait experienced higher mortality (6.6%) than those caught on artificial baits (0%), and wire fish baskets caused higher mortality (34.0%) than live wells (7.6%). The mortality of bluegills held in live wells was higher for the 3‐ and 5‐h retention times than for the 1‐h treatment. The probability of dying from catch and release decreased with increasing fish length. We applied our results to a bluegill population under a restrictive harvest regulation consisting of a 203‐mm minimum size limit and a 10‐fish daily bag limit. Under these restrictive regulations, fish lost from catch and release represented 27.4% of the total kill (harvest and hooking mortality). While catch‐and‐release angling can cause some mortality, it does not appear from our study that releasing fish will have a deleterious effect on bluegill populations.

Bycatch and discard mortality in commercially caught blue sharks Prionace glauca assessed using archival satellite pop-up tags

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 387:241-253 (2009) - DOI: https://doi.org/10.3354/meps08109 Bycatch and discard mortality in commercially caught blue sharks Prionace glauca assessed using archival satellite pop-up tags Steven E. Campana1,*, Warren Joyce1, Michael J. Manning2,3 1Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia, Canada B2Y 4A2 2National Institute of Water and Atmospheric Research Ltd (NIWA), Private Bag 14901, Kilbirnie, Wellington, New Zealand 3Oceanic Fisheries Programme, Secretariat of the Pacific Community (SPC), BP D5, 98848 Noumea Cedex, New Caledonia *Email: campanas@mar.dfo-mpo.gc.ca ABSTRACT: Blue sharks Prionace glauca are the most frequently discarded fish species during commercial pelagic longline fishing operations worldwide, yet their post-release mortality rate has never been measured. A generalized linear model of 12404 blue sharks observed during the Canadian Atlantic pelagic longline swordfishery suggested a hooking mortality of 12 to 13%, yet scientific examination of 902 of these sharks indicated that hooking mortality was actually higher. A random sample of 40 of these blue sharks were tagged with satellite pop-up archival transmission (PAT) tags, then monitored for periods of up to 6 mo after release. All of the surviving sharks exhibited a depth-holding recovery behaviour for a period of 2 to 7 d after release. All healthy sharks survived, while 33% of those that were badly injured or gut hooked subsequently died. Overall blue shark bycatch mortality in the pelagic longline fishery was estimated at 35%, while the estimated discard mortality for sharks that were released alive was 19%. Survival time models indicated that 95% of the mortality occurred within 11 d of release, indicative of death by trauma rather than starvation. The annual blue shark catch in the North Atlantic was estimated at about 84000 t, of which 57000 t is discarded. A preliminary estimate of 20000 t of annual dead discards for North Atlantic blue sharks is similar to that of the reported nominal catch, and could substantially change the perception of population health if incorporated into a population-level stock assessment. KEY WORDS: Discard mortality · Hooking mortality · Tagging · Bycatch · Satellite tags Full text in pdf format See Comment and Reply Comment on this article PreviousNextCite this article as: Campana SE, Joyce W, Manning MJ (2009) Bycatch and discard mortality in commercially caught blue sharks Prionace glauca assessed using archival satellite pop-up tags. Mar Ecol Prog Ser 387:241-253. https://doi.org/10.3354/meps08109 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 387. Online publication date: July 28, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

Size Selectivity, Injury, Handling Time, and Determinants of Initial Hooking Mortality in Recreational Angling for Northern Pike: The Influence of Type and Size of Bait

AbstractWe examined the relationship between bait and lure size and type and body size, injury, and handling time for northern pike Esox lucius, an important recreational fisheries resource in much of North America and Europe. Bait type and size were significantly related to the size of fish captured and hooking location. Hooking in critical locations (i.e., gills, gullet) was more likely to occur with natural bait, soft plastic shads and jigs, and spoons than with spinners and wobblers (i.e., plugs). Small baits (&lt;75 mm) were more likely to hook the fish in the gills and less likely to hook the fish in the upper jaw than larger baits. It took longer to remove hooks from gills than from other hooking locations. Frequency of bleeding was related to depth of hooking but was unrelated to fish size, bait type, bait size, or fishing method. Initial mortality of northern pike was low (mean ± 95% confidence interval = 2.4 ± 1.5%), and hooking mortality was significantly related to the level of bleeding as a proxy for severity of injury. Results of this study suggest that using large artificial lures and large natural baits can effectively reduce the incidence of hooking small northern pike (i.e., those that are sublegal in some jurisdictions). However, the use of natural bait can also result in a higher incidence of deep hooking, which in turn increases the likelihood of injury and bleeding. This study revealed the complexity associated with using bait and lure restrictions to complement standard harvest regulations in northern pike recreational fisheries.