Baited Hooks Research Articles

Recreational fishing in the lower basin of the Santa Cruz river(Patagonia, Argentina) in the face of damming scenarios

The Steelhead ecotype (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) have promoted a recreational fishery in the Santa Cruz river, the last large free flowing river of Patagonia. However, two dams are being built upstream in the middle course, potentially affecting the life cycle of these anadromous salmonids. The study describes the dynamics of the recreational fishing of the Santa Cruz river around Piedrabuena city and anglers perceptions, discussing its trends according to possible river connectivity scenarios. The fishery was assessed through a monthly year-round field sampling from April 2018 to April 2019, developing instantaneous angler counts, discriminating fishing methods, effort, and catch per unit effort; also, in situ interviews were used to collect information on anglers’ motivations and perceptions. In addition, information on fishing tournaments was used. Three fishing zones (FZ) were identified near Piedrabuena city: FZ-1, located downstream where anglers used baited hook and line to catch the native marine Patagonian blenny (Eleginops maclovinus); FZ-2, located in the town where baited hook and line, spinning, and fly-cast are used to catch Patagonian blenny and salmonids; FZ-3 located upstream the town, where fishing effort was mainly directed to salmonids employing spinning and fly-cast. Fishing effort showed a seasonal pa�ern with high values from March to May and September to October, agreeing with Steelhead and Chinook salmon runs, respectively. The most relevant motivations for anglers were nonoriented catch variables. Anglers preferred the capture of salmonids over native species, considering dams to be a major threat to fishery. Although a postdamming scenario could allow the adult salmonids to migrate upstream, the current reproduction grounds of Steelhead will be flooded, and juveniles and adults of both species will be hindered in their downstream migration to sea. These aspects seem to seriously compromise the future of these unique fisheries.

Use of biodegradable materials to reduce marine plastic pollution in small scale coastal longline fisheries

Pollution from lost, abandoned, or discarded fishing gear is recognized as a global nature conservation concern. Longlining with hooks is a commonly applied fishing method in fisheries around the world. The longline gear consists of a mainline with a number of baited hooks that are attached to it by thinner twine (snoods) which are often made of plastic material such as polyamide (nylon) or polyester that degrades very slowly in the marine environment. During longline fishing, some of the snoods are lost at sea contributing to marine macro- and micro-plastic pollution. The extent of the snood loss is often unknown and can vary between different longline fisheries and fishing grounds. In this study, we estimated and compared the risk for the biodegradable and nylon snood loss in an Adriatic small scale longline fishery. Further, we compared the catch composition and estimated catch efficiency between biodegradable and nylon snoods for capture of common pandora (Pagellus erythrinus), two-banded seabream (Diplodus vulgaris) and axillary seabream (Pagellus acarne). The risk for nylon snood loss in this longline fishery (3 % for each snood for each deployment), demonstrate that the use of more environmentally friendly materials is necessary for nature conservation. No significant differences between the performance of the two materials regarding snood loss rate, hook loss rate, catch efficiency and catch composition were found during short-term usage in the fishery. Based on these results, future long-term testing is encouraged to investigate whether this promising performance of the biodegradable snood material is persistent over longer fishing periods.

Neophobic behavioural responses of parasitised fish to a potential predator and baited hook

Many juvenile fish show essential avoidance of predators but are also faced with the need to show risky asset-acquiring behaviour, such as trying new food sources, many of which are known to be influenced by parasite infection. Here, we investigated the links between parasite infection, anti-predator behaviour and neophobia towards a novel food presented on a baited hook in fish. Juvenile Spangled perch (Leipotherapon unicolor) undertook two behavioural tests in our laboratory, before being dissected and examined for external and internal parasites. We used an adapted conditioned place avoidance (CPA) paradigm to examine responses to a predator fish and in a separate test, we examined neophobia of a baited hook. Of the 69 Spangled perch studied, 27% of fish were uninfected and at least one of nematodes, Protozoa/Myxozoa or Monogenea were found in the remaining fish. Fish spent less time in the side of the tank where the predator was previously encountered, than before encounters, indicating that fish can learn to avoid locations where predators were previously observed. We found that fish spent longer in the side of the tank where the predator was visible than in the same side of the tank in earlier trials without the predator, supporting previous studies showing that fish actively approach and engage in predator inspection. Fish infected with Protozoa/Myxozoa and camallanid nematodes were less likely to enter the side of the tank with the predator than uninfected fish, suggesting a reluctance to approach a predator in these infected fish. However, Protozoa/Myxozoa and camallanid infected fish bit the baited hook sooner than uninfected fish, possibly indicating less neophobia of the baited hook in fish with these infections. Avoiding to approach a predator yet reduced neophobia to novel foods in some infected fish suggest that parasites do not exert a general, overall, effect on risk aversiveness. Instead, changes in neophobic behaviour appear complex and we discuss the possibility that parasite-induced changes in fish behaviour may be modulated by altered hunger levels and reduced locomotion brought about by illness.

Fussy eaters, bait loss and escapees: How reliable are baited-hook assessments of shark abundance in shallow, coastal waters?

Sets of baited hooks decrease in fishing efficacy over time as catch accumulates and bait is lost, and this complicates the quantification of fishing effort for species abundance calculations. Although hook-timers facilitate a more accurate estimation of fishing time, they cannot provide taxonomic information in the case of escapees or bait loss, nor can they provide information on animals that approach the gear but do not physically engage with it. To overcome these limitations, the present study attached sport action cameras to baited drumlines during a catch-and-release survey of sharks in the shallow, coastal waters of the eastern Caicos Bank, Turks and Caicos Islands. Overall, the true fishing time was found to be appreciably less than the apparent fishing time and more sharks approached or interacted with the gear than were successfully captured by it. Furthermore, shark-gear interactions varied by species while the amount of bait loss differed between deployment areas. Taken together, these findings suggest that baited-hook surveys underestimate shark abundance and that the magnitude of this error varies by species and habitat type.

Ghost Fishing by Abandoned Trotlines in a Simulated and Actual Reservoir

AbstractGhost fishing is described as the continuation of fishing by abandoned fishing gear. The freshwater trotline, a passive gear that is routinely found abandoned, has never been evaluated for its ability to ghost fish. We tested the effectiveness of top‐water set trotlines to ghost fish in (1) a simulated reservoir (i.e., hatchery ponds) and (2) an actual reservoir. In our simulated reservoir, we exposed Channel Catfish Ictalurus punctatus to baited and bare (unbaited) hooks of two hook styles (circle and “J”) during the winter and summer seasons. We found that in the simulated reservoir, catch rates of baited hooks (mean = 18.4 fish per 24 hooks, standard error [SE] = 2.13) did not differ significantly from bare hooks (mean = 15.3 fish per 24 hooks, SE = 1.77), circle hooks were 1.5 times more effective at catching fish than “J” hooks (χ2 = 4.19, df = 1, P = 0.041), and fish were retained longer in the winter (mean = 12.7 d, SE = 0.66) compared to the summer (mean = 2.8 d, SE = 0.21). We used the actual reservoir portion to examine the long‐term fishability and the overall longevity of the trotline gear during the same seasons. Catch was highest during the first week and decreased with time. Trotlines caught mostly fish (81.6%), and most catch (>68%) occurred after the initial bait was lost. Winter‐set trotlines captured more organisms (11.6 per 25‐hook trotline; SE = 2.05) than summer‐set trotlines (5.2; SE = 0.99). Trotline longevity was assessed by counting the fishable hooks through time. Longevity differed between seasons (P = 0.0039), and winter‐set trotlines lasted longer (50% hook loss at 52 d, 95% confidence interval [CI] = [49, 77]) than summer‐set trotlines (32 d, 95% CI = [24, 36]). This study confirms that abandoned freshwater trotlines do ghost fish and will continue for months after they are initially set.

Slow sink rate in floated-demersal longline and implications for seabird bycatch risk.

Bycatch of birds in longline fisheries is a global conservation issue, with between 160,000-320,000 seabirds killed each year, primarily through being caught and drowned as they attempt to snatch baits off hooks as they are set. This conservation issue has received significant recognition in southern hemisphere longline fisheries over the past several decades, largely due to the impact on highly charismatic and highly threatened birds, notably Albatrosses. As a result, the use of effective mitigation measures has been subject to fisheries regulations to reduce seabird bycatch from longliners in a number of national jurisdictions and in several Regional Fisheries Management Organisations (RMFOs). While mitigation measures have been mandated in a number of north Pacific longline fisheries, this is largely not the case in north Atlantic longline fisheries. This includes vessels using floated-demersal longlines in the North-East Atlantic longline fishery targeting European Hake Merluccius merluccius, in which high levels of seabird bycatch are estimated. In this paper, we analysed the sinking speed of a floated-demersal longline used to target European Hake in the offshore waters of Scotland, to determine potential bycatch risks to seabirds. We deployed Time Depth Recorder devices at different points of the gear. We assessed how this gear performed in comparison to the best practice minimum sink rate of 0.3 m/s recommended by the Agreement on the Conservation of Albatrosses and Petrels (ACAP) to limit bird access to baited hooks. We found that the average sinking speed of the floated-demersal longline was substantially slower than the ACAP recommendation, between two and nine times slower in non-weighted parts of the gear down to 10m water depth. Our work also found that the sink rate is particularly slow in the top 2m of the water column, increasing with depth and stabilizing at depths over 10m, presumably a consequence of propeller wash behind the vessel. We calculated that the distance astern of the vessel for hooks to sink beyond susceptible seabirds' reach largely exceeds optimum coverage of best practice design Bird Scaring Lines (100 m). Our results indicate that hooks from floated-demersal longlines are therefore readily open to seabird attacks, and as a result, present a clear bycatch risk. Research is needed to adapt existing mitigation measures to floated-longlines and to develop novel mitigation approaches to improve the sink rate of the gear without impacting target fish catch.

Effect of hook type and hook setting method on deep‐hooking rates when bait fishing for trout in lentic waters

AbstractFishing with circle hooks along with prescribed hook‐setting methods can reduce deep‐hooking rates in some fisheries, but baited circle hooks have not been evaluated in stillwater trout fisheries. Deep‐hooking rates and catch probabilities were compared for cutthroat trout Oncorhynchus clarkii​ (Richardson), rainbow trout Oncorhyncus mykiss (Walbaum), cutthroat × rainbow trout hybrids, and brook trout Salvelinus fontinalis (MItchill) caught using three types of baited hooks (circle, intermediate circle and traditional J) and two hook‐setting methods (active and passive) in several lakes containing naturally reared trout. Hook type had a negligible effect on deep‐hooking rates, which averaged 20%. Actively setting the hook and fishing with a bobber both reduced deep‐hooking rates, regardless of hook type. Larger fish were deeply hooked more frequently regardless of hook type. Catch probabilities were higher when active rather than passive hook‐setting was used, particularly in combination with intermediate circle hooks. The present results, which indicate that circle hook use did not reduce deep hooking in lentic settings, contrast earlier studies done in lotic waters. Therefore, before proposing hook‐type regulations intended to reduce deep hooking, fisheries managers should consider waterbody type in addition to fishing methods, fish size and species.

Reducing bycatch impacts in recreational fisheries: Case study examining terminal tackle in the multispecies Gulf of Maine groundfish fishery

AbstractTerminal tackle regulations can be a valuable tool for fisheries management, especially in multispecies fisheries where bycatch and discards are common issues. In the Gulf of Maine, recreational anglers frequently discard critically depleted Atlantic cod Gadus morhua L. as bycatch when targeting the abundant haddock Melanogrammus aeglefinus (L.) stock. The present study investigated species catch composition, catch rates and animal welfare across various terminal tackle setups, and aspects of capture and handling with the goal of reducing bycatch and discard mortality. Overall, 2558 cod and 4266 haddock were captured with six terminal tackle setups in the western Gulf of Maine from April to October 2018. Along with angler experience and capture depth, lure type primarily influenced species catch composition and catch‐per‐unit‐effort; hook types additionally influenced hook‐removal times and physical injuries to fish. Results indicate that using baited hooks can both promote haddock catch and reduce cod bycatch, with specific hook types promoting increased survival.

Diving behaviour of albatrosses: implications for foraging ecology and bycatch susceptibility

Diving is an ecologically important behaviour that provides air-breathing predators with opportunities to capture prey, but that also increases their exposure to incidental mortality (bycatch) in commercial fisheries. In this study, we characterised the diving behaviour of 26 individuals of three species, the black-browed albatross Thalassarche melanophris, grey-headed albatross T. chrysostoma and light-mantled albatross Phoebetria palpebrata, breeding at Bird Island, South Georgia. Individuals were tracked using Global Location Sensor (GLS)-immersion loggers and time-depth recorders (TDRs) and, for two species, Global Positioning System (GPS) loggers. Although the TDRs recorded 589 dives (defined in this paper as submersion > 1 m), average dive depths and durations were just 1.30–1.49 m and 2.5–3.3 s, respectively, for the three species. In addition, many individuals (22% of black-browed, 20% of grey-headed, and 57% of light-mantled albatrosses; total n = 9, 10 and 7 individuals, respectively) did not dive at all. Most dives occurred at the distal end of foraging trips and were rare during the commuting phase. No dives took place in darkness, despite long periods spent on water at night. The limited and shallow dive activity contrasts with impressions from a previous study using capillary-tube depth gauges (which are less accurate than TDRs) and has implications for the susceptibility of albatrosses to bycatch on longlines. This study provides further support for regulations requiring night setting and increased sink rates of baited hooks to help mitigate albatross bycatch.

Improved line weighting reduces seabird bycatch without affecting fish catch in the Brazilian pelagic longline fishery

Abstract Increasing the sink rate of baited hooks by adding weights in close proximity to the hook is crucial to reduce seabird mortality in pelagic longline fisheries. However, weights placed next to the hook are a cause for concern for fishing crew because they can fly back in the event of a line break, injuring deck crew. Lumo Leads, an alternative weight system designed to slide in the event of a line break, and therefore prevent accidents, were trialled in pelagic longline fisheries off southern Brazil. Four fishing trips were conducted and 26,377 hooks sampled to compare sink rates, seabird bycatch rates and catch rates of target species between three treatments: (1) 60 g Lumo Lead attached at 1.0 m from the hook; (2) 60 g Lumo Lead at 3.5 m; and (3) 60 g leaded swivels at 3.5 m from the hook. A Lumo Lead placed at 1.0 m from the hook resulted in a faster sink rate and caught fewer seabirds (0.11 birds per unit of effort [BPUE]) when compared with a Lumo Lead (0.33 BPUE) or weighted swivel (0.85 BPUE) placed at 3.5 m. The bycatch with Lumo Lead placed at 1.0 m from the hook was 90% lower than the bycatch of Lumo Lead or weighted swivel placed at 3.5 m combined. There was no difference in the catch rates of target species between the three treatments. These findings support a growing body of evidence that placing weights close to the hook reduces seabird bycatch without affecting the catchability of the target species. The high seabird bycatch rates recorded despite night setting and recommended line weighting regimes reinforces the need of simultaneous deployment of a toriline with these other two mitigation measures to reduce seabird bycatch to negligible levels in the south‐west Atlantic.

Mitigating bycatch of threatened seabirds: the effectiveness of branch line weighting in pelagic longline fisheries

AbstractSubstantial numbers of seabirds are bycaught each year in pelagic longline fisheries. Increasing the sink rate of baited hooks by reducing the distance between the hook and the weight of the branch lines (leader length) has enormous potential to mitigate this bycatch. Here, we test the effect of reducing the leader length on seabird attacks on baited hooks and bycatch rates plus the effect on fish catch rates on the Uruguayan slope. Two branch line configurations were tested: a control treatment (CT) of the standard branch lines used in the Uruguayan fishery, with 75 g swivels on 4.5 m leaders; and two experimental treatments (ET) consisting of branch lines with either a 60 g or 65 g weight on 1 m leaders. Seabird attacks were assessed during 34 daylight longline sets (100–150 hooks each) without a bird scaring line (BSL) comparing two treatments: CT versus 65 g ET. The fish catch was assessed during 224 paired sections (75 vs. 75 hooks) from 109 fishing sets deployed mostly during the night and with a BSL, comprising 77 pairs of CT versus 60 g ET and 147 pairs of CT versus 65 g ET. The number of primary (231 vs. 91) and multiple (50 vs. 14) attacks were significantly higher in the CT compared with the 65 g ET respectively. The seabird bycatch rate was 42.5% lower in the 65 g ET than in the CT. The use of branch lines with short leaders did not affect the catch of target species. This study conducted in an area of high bycatch risk provides strong experimental support for the use of branch line weighting to reduce seabird bycatch. Based on the observed bycatch rates, this measure should be implemented in combination with other mitigation measures. The simultaneous use of branch line weighting, a BSL and night setting resulted in zero seabird bycatch.

Setting baited hooks by stealth (underwater) can prevent the incidental mortality of albatrosses and petrels in pelagic longline fisheries

For many decades pelagic longline fisheries have been responsible for the deaths of large numbers of seabirds worldwide. Baited hooks deployed onto the sea surface attract seabirds to fishing vessels leading to attacks on baits, capture and death by drowning. An alternative is to deploy baits underwater where they are less detectable, more difficult to reach and less likely to be taken by seabirds. In 2010 and 2012 proof-of-concept experiments were conducted in the Uruguayan pelagic longline fishery with a newly developed device designed to set baits underwater. The experiments examined the differences between setting baits at the sea surface and setting baits underwater with regard to the abundances of seabirds following the vessel, incidences of attacks on baits and mortality. Underwater setting led to marked reductions in the numbers of seabirds following the fishing vessel and attacks on baits, the behavioural precursors to mortality. Mortality rates of seabirds on baits set to the relatively shallow depth of 4 m were 87% lower than on baits set at the surface. No seabirds were caught on baits released 10 m underwater, a reduction of 100% compared to the surface setting mortality of 11.6 birds/1000 hooks. No differences were detected between the two setting methods in the catch rates of target and non-target fish species. The evidence from the experiments, combined with the known dive depths of the white-chinned petrel (Procellaria aequinoctialis), a deep diving, difficult-to-deter species, suggests that baits released 10 m underwater could reduce the incidental mortality of albatrosses and petrels to negligible levels.

Comparative Abundance, Species Composition, and Demographics of Continental Shelf Fish Assemblages throughout the Gulf of Mexico

AbstractWe analyzed the results of the first comprehensive, systematic, fishery‐independent survey of Gulf of Mexico (GoM) continental shelves using data collected from demersal longline sampling off the United States, Mexico, and Cuba. In total, 166 species were sampled from 343 longline sets during 2011–2017, which deployed 153,146 baited hooks, catching 14,938 fish. Abundance, species richness, and Shannon–Wiener diversity indices by station were highest in mid‐shelf depths (~100 m), declining by about half in deeper waters. Six spatial assemblages were identified by testing the results of cluster analysis using similarity profile analysis and then plotting the geographic location of identified station clusters. A high degree of depth‐related and horizontal zonation was evident for demersal fish species. Multispecies CPUE (number per 1,000 hook‐hours) was highest off the north‐central (NC) and northwestern (NW) GoM and lower on the West Florida Shelf (WFS), Cuba (CUB), Yucatan Peninsula (YP), and southwestern (SW) GoM. Snappers and groupers were most abundant in the WFS and CUB, while elasmobranchs were the dominant taxa in the NC and NW GoM. Pelagic species were relatively rare everywhere (owing to the use of demersal longline gear), but were most dense off CUB. Species richness was highest in the NC and WFS subareas and lowest in the NW and CUB. Slopes of multispecies size spectra, which integrated mortality, recruitment, growth, and species interactions among size‐groups, were shallowest in the NW and NC GoM and steepest off the WFS and YP. These results provide a basis for evaluating the relative resiliency potential of species assemblages across the continental shelves of the GoM, and thus for identifying subareas that are most vulnerable to acute and chronic perturbations from cumulative effects of fishing, climate change, pollution (including oil spills), habitat loss, and invasive species.

Seabird bycatch mitigation trials in artisanal demersal longliners of the Western Mediterranean.

High numbers of seabirds are killed annually worldwide in longline fisheries. In the Mediterranean, this mortality is seriously affecting the viability of seabird populations, in particular of the three endemic shearwaters. Even so, there is currently no specific seabird mitigation requirements for the longline fleet operating in this area. From 2013 to 2014, we assessed the efficiency and practical applicability of four mitigation measures on artisanal demersal longliners targeting European hake (Merluccius merluccius) in the western Mediterranean: night setting, tori line, weighted lines and artificial baits. We performed fifty-two pairs of experimental (with the tested mitigation measure) and control settings (without any measure), and compared their effects on seabird interactions and fish catches. In addition, we estimated the longline sink rates and the seabird access area to baited hooks in different longline configurations. Night setting reduced bycatch risk without affecting target and non-commercial fish catches. The tori line may have reduced the bycatch risk by displacing bait attacks beyond the end of the line, but at this distance shearwaters could still access to the baits and the streamers did not deter birds under calm wind conditions. Weighted lines increased sink rate, but it resulted in only a minor reduction of the seabird access window to baited hooks and led to some operational problems during the setting. Artificial baits substantially reduced commercial catches. Moreover, the seabird access to the baited hooks was influenced by the longline configuration, the setting speed and the relative position to the floats and weights. So far, night setting stands out as the best mitigation measure for reducing bycatch levels without compromising target catches in demersal longliners. Ideally, these results should be confirmed in longliners targeting species other than European hake.

Habitat-specific performance of vertical line gear in the western Gulf of Mexico: A comparison between artificial and natural habitats using a paired video approach

Gear performance is often assumed to be constant over various conditions encountered during sampling; however, this assumption is rarely verified and has the potential to introduce bias. We used fishery-independent vertical line surveys to evaluate whether gear efficiency and selectivity is similar while assessing reef fish populations at oil and gas platforms, artificial reefs, and natural banks in the western Gulf of Mexico. We conducted 192 vertical line sets with cameras placed on a subset of these deployments to validate any differences in efficiency among habitat types. Red snapper (Lutjanus campechanus) accounted for 93% of the catch. No difference in red snapper CPUE among habitats was detected. When evaluating fish size, 8/0 and 11/0 hooks sampled significantly larger red snapper at natural banks than at artificial habitats. While CPUE was similar among all hooks at artificial habitats, CPUE at natural banks was lower for shallower hooks and increased towards the bottom hooks along the backbone. At all habitats, red snapper TL decreased from shallow to deep hook positions. Simultaneous camera deployments revealed other processes affecting efficiency such as bait removal and depredation. Vermilion snapper (Rhomboplites aurorubens) were effective at removing bait while avoiding capture. Perhaps related to this observation, Red snapper CPUE was negatively correlated with the vermilion snapper video index of abundance. Video confirmed gear saturation was prevalent (70% of deployments), occurring more frequently on artificial habitats. Furthermore, the time fished was effectively “shorter” at artificial habitats as the number of available baited hooks declined rapidly. These results point towards higher relative abundance at artificial habitats; however, the prevalence of saturation indicates vertical line CPUE may not always be proportional to true abundance, hindering our ability to detect differences at the scale examined in this study. Vertical line surveys should evaluate the prevalence of saturation as inferences regarding relative abundance may be compromised when this information is unknown.

Conservation of small hairtail Trichiurus japonicas by using hooks with large artificial bait: effect on the trolling line fishery

Overfishing has reduced the stock of hairtail Trichiurus japonicus around the Bungo Channel, Japan. To determine whether using larger bait in the trolling line fishery could avoid catching small/undersize hairtail, we developed and trialled a new large artificial bait (a soft plastic bait, 6 inches long). A traditional lure with natural bait (type-1), a new lure of the new artificial bait hook without natural bait (type-2), and a new lure with natural bait (type-3) were tested in fishing operations around the Bungo Channel. Compared with type-1, type-2 and type-3 caught fewer undersized and immature female individuals. The number of fish caught, yield, and composition of commercial size grades per recruitment were calculated from field data for each lure and compared. The catch sizes (number of fish per recruitment) were smaller for type-2 and type-3 than for type-1, but yield per recruitment was higher for type-3 than for type-1. Compared with type-1, type-2 and type-3 caught more large individuals, which are more valuable. The newly developed artificial bait conserves hairtail stocks by targeting larger fish, which is economically beneficial for the hairtail trolling line fishery.

Recreational fishing impacts on threatened river sharks: A potential conservation issue

SummaryThe Adelaide River in Australia's Northern Territory is a popular recreational fishing area, as well as habitat for threatened and protected river sharks (Glyphis species). Both the Critically Endangered Speartooth Shark (Glyphis glyphis) and Endangered Northern River Shark (Glyphis garricki) are identified here in illegal catches from recreational angling. The identification of a decayed shark specimen using a DNA barcoding‐like approach is the first such application to the identification of protected sharks in a recreational fishery. While the extent of catches by recreational anglers is unknown, the threatened status of these sharks, their suspected low population sizes, restricted distributions and importance of the Adelaide River as a nursery area call for the consideration of this as a potential conservation issue. As such, appropriate measures should be taken to reduce interactions with recreational anglers. The primary target species in the river is the iconic sportfish, Barramundi, which is predominantly caught by unbaited lure. Sharks are rarely caught on lure, allowing an opportunity for mitigation to focus on a fishing activity (baited hooks) which would limit any regulatory impact on popular lure fishing. Potential mitigation measures range from increased angler education and compliance checks, to the implementation of a spatial closure to baited hook fishing (a lure‐only zone). Such measures may assist in meeting a stated objective of the Australian Government's river shark Recovery Plan to ‘reduce and, where possible, eliminate adverse impacts of recreational fishing'.

Sublethal effects of angling and release on golden perch Macquaria ambigua: implications for reproduction and fish health.

The present study tested the hypothesis of no delayed sublethal effects of mild angling and release on the feeding, growth, somatic condition and gonadal development of golden perch Macquaria ambigua during gametogenesis. Subsamples of adult M. ambigua (n = 17-21 of 207), originally captured from the wild and stocked into ten 0·1 ha earthen ponds, were angled and released during early and late gametogenesis. Wild samples that were concurrently collected throughout the experiment underwent rapid and synchronous gonadal development and many spawned. While no spawning occurred in the ponds, most M. ambigua underwent normal gonadal development to maturity, including the angled fish. Angled fish also fed, maintained condition and actually grew faster than non-angled captive controls. Although females that were angled during late gametogenesis more readily ingested and retained baited hooks, neither their subsequent condition nor gonadal development was significantly affected. The predominance of null results was attributed to the combined effects of the flexible reproductive strategy of M. ambigua, the benignness of mouth hooking and immediate release, and possible methodological issues arising from differential hooking success of more aggressive and resilient individuals. The findings support earlier catch-and-release research, but contrast with reports of acute reproductive effects following capture and handling for aquaculture broodstock. This discrepancy highlights the need for research to specifically address welfare questions relevant to recreational fisheries across various species and angling scenarios.

A Review of the Welfare Impact on Pinnipeds of Plastic Marine Debris

Uncounted, and usually unobserved, numbers of pinnipeds find themselves entangled in lost fishing gear, monofilament line, nets, rope, plastic packaging in the ocean or on the shoreline. These animals may carry debris wrapped around themselves for long periods, and often die as a result, sometimes from deep chronic wounds. The pinniped species most affected by this modern and manmade phenomenon are fur seals, monk seals, and California sea lions, and to a lesser extent grey, common and monk seals. Entanglement rates described range up to 7.9% of local populations annually, and the common entangling materials; packing bands, fragments of lost net, rope, monofilament line, fishery flashers and lures, long-line fishing gear, hooks and line, and bait hooks are discussed. Awareness of this issue is increasing, and local action is reported to have made measurable differences in entanglement rates, however, plastic material in the ocean is likely to be long lived, and will leave many entangled pinnpeds unreported and result in a hidden and potentially significant effect on wild animal welfare.

Synergistic and interactive effects of angler behaviour, gear type, and fish behaviour on hooking depth in passively angled fish

Despite a growing body of literature on the impacts of recreational fisheries on wild populations, surprisingly little is known regarding how individual differences in fish behaviour and their interaction with a baited hook influences hooking injury. We used an underwater video camera, fixed to the fishing line, to record the behaviour of wild sunfishes (Lepomis spp.) as they approached and attacked one of four treatments of baited hook used under a passive angling scenario. Angler reaction time was measured as the difference between the fish strike and hook set. Length-corrected hooking depth was evaluated as a function of multiple putative explanatory variables. Angler performance (hooksets/min) varied over the two day study, where hooksets/min decreased with small hooks and increased with large hooks. Model selection and model averaging revealed the top models included the terms: angler reaction time, approach to bait (cautious, deliberate, aggressive), hook size (small or large), and the interaction between approach to bait and hook size. The model-averaged fitted values indicated that length-corrected hooking depth increased most dramatically with angler reaction time when fish aggressively attacked a baited hook. A cautious approach to a large baited hook led to a deeper length-corrected hooking depth than a similar approach to a small baited hook. These results illustrate synergistic and interactive relationships among factors known to influence impairment, injury, and mortality in caught and released fish. Of particular novelty was our ability to assess the variation in how fish behaviour influences injury in a catch-and-release fishery using underwater cameras, which suggests that this approach holds promise in fisheries science.