Estudio comparativo de pesca pelágica recreativa entre las artes de línea de mano y curricán en el golfo de Omán, Irán

The choice of fishing gear and catching strategy should be taken into consideration in the management of fish stocks. Here, paired fishing trials in a pelagic recreational fishery compared the catch composition, catch rate and size selectivity between handline and trolling fishing methods in Iranian coastal waters of the Gulf of Oman. Total catch rate was 1.06 fish hr–1 vs 0.88 fish hr–1 for handline and trolling, respectively, a 17% difference which was significant (p < 0.05). Generally, the handline method captured more fish than trolling for most species, but size selectivity tended to be species-specific per gear type. The handline fishing method captured larger talang queenfish (Scomberoides commersonnianus), while trolling captured larger narrow-barred Spanish mackerel (Scomberomorus commerson), pickhandle barracuda (Sphyraena jello) and Indian threadfish (Alectis indicus). Technical measures, such as gear restrictions, could be applied to recreational pelagic fisheries management in the Gulf of Oman. Such measures could improve species-specific exploitation patterns.La selección del equipo de pesca y la estrategia de captura deben ser consideradas en la gestión de stocks pesqueros. En el presente estudio se muestran resultados de tipos, tasas y selectividad de talla de las capturas en una experiencia comparativa de artes de pesca en aguas costeras del golfo de Omán, Irán. Las tasas de captura finales para las artes de línea de mano y curricán fueron de 1.06 y 0.88 peces h–1 respectivamente, mostrando un significativo 17% de diferencia entre ambas (p < 0.05). Por lo general, el arte de línea de mano resultó en una mayor tasa de captura multiespecífica, sin embargo la selectividad de talla se observó arte-dependiente. En el arte de línea de mano se observaron capturas de mayor talla para la especie “talag queenfish” (Scomberoides commersonnianus), mientras que para el curricán fueron la caballa o verdel (Scomberomorus commerson), barracuda (Sphyraena jello), e “Indian threadfish” (Alectis indicus). En conclusión, la implementación de medidas técnicas, como restricciones en las artes de pesca, podrían ser aplicadas en la regulación de la normativa de pesca recreativa para la gestión general pesquera con el objetivo de la mejora en los patrones de explotación especie-específica del golfo de Omán

Sailfish (Istiophorus platypterus) Habitat Utilization in the Southern Gulf of Mexico and Florida Straits with Implications on Vulnerability to Shallow-Set Pelagic Longline Gear

A total of 19 pop-up satellite archival tags (PSATs) were deployed on sailfish in the southern Gulf of Mexico between 2005 and 2007 aboard a commercial pelagic longline vessel (n = 18) and a recreational rod-and-reel vessel (n = 1). All PSATs were programmed to collect pressure (depth), temperature, and light-level data for 10 days at approximately 90-second intervals. These point-level data were not summarized prior to transmission, allowing the reconstruction of vertical movement patterns. Three tags suggested mortality events and were excluded from subsequent analyses. We present the preliminary data analyses from the remaining 16 PSATs. Sailfish are primarily associated with the upper surface waters at 20 m or less depth. However, sailfish also exhibited numerous repeated short-duration vertical movements below the local thermocline to depths of 50-150 m. The depth utilization from these tagged fish coincide with the actively fished depths of shallow-set pelagic longline gear, yet appear to be shallower than the depths of settled deep-set gear used to target bigeye tuna

Sailfish Habitat Utilization and Vertical Movements in the Southern Gulf of Mexico and Florida Straits

Pop-up satellite archival tags (PSATs) were deployed on 19 sailfish Istiophorus platypterus captured in the southern Gulf of Mexico and Florida Straits between 2005 and 2007 on commercial pelagic longline gear (n = 18) and recreational rod-and-reel gear (n = 1). The data from three tags indicated mortality events and were excluded from subsequent analyses. All PSATs were programmed to collect pressure (depth), temperature, and light-level data for 10 d at approximately 90-s intervals. These transmitted point data subsequently allowed the reconstruction of vertical movement patterns. The remaining 16 PSAT data sets indicate that sailfish are primarily associated with the upper surface waters within the top 20m(75.7% of total time during the day versus 46.7% at night) but undertake numerous short-duration vertical movements below the local mixed layer to depths of 50-150 m, presumably to feed. Analyses of 2,279 individual vertical movements among all 16 tagged sailfish indicated two distinct types (short-duration V and longer-duration U movements) similar to those reported for white marlin Kajikia albida. Sailfish also exhibited movement type differences between diel periods (having higher proportions of V movements in daytime), suggesting directed foraging at depth. Although short-duration movement to depths by these tagged fish contribute a small percentage of the total time at depth, these depths overlap with themonitored shallow-set pelagic longline gear depths actively targeting swordfish by the vessel in the local fishery. These results suggest that time-at-depth histograms alone may be insufficient to capture feeding motivations at depth and, therefore, true interaction potentials between individual sailfish and pelagic longline gear

Increased catches of snow crab (Chionoecetes opilio) with luminescent-netting pots at long soak times

Luminescent netting increases the catch rate of snow crabs (Chionoecetes opilio) over short soak times (1 d), however the commercial fishery often requires longer soak periods, up to1 week. Building on previous research, this study investigated the catch efficiency and size selectivity of pots with luminescent netting over long soak times (144–336 h) in the inshore snow crab fishery of Newfoundland, Canada. A total allowable catch and individual quota allocation management system for snow crab is regulated in Canada and using luminescent netting to increase catch rates would reduce the carbon footprint of the fishery by reducing days fished. Our results showed that luminescent pots had a 21.6 % and 18.3 % higher catch-per-unit-effort (CPUE; number of crabs per pot) of legal-sized crab and sub-legal sized crab, respectively, than control pots; with no difference for soft-shelled crab. Additionally, no significant differences were shown for size selectivity over the range of carapace widths observed between luminescent and control pots. Little other bycatch (female snow crab and unwanted species) were caught in either pot treatments. This study shows that luminescent netting increases the efficiency of the snow crab fishery, which provides economic and environmental benefits.publishedVersio

Effect of light-emitting diodes (LEDs) on snow crab catch rates in the Barents Sea pot fishery

Snow crab (Chionoecetes opilio) has become an important species for the Norwegian seafood industry since its first commercial harvest in 2012. However, periodically catch rates can be low, causing a financial strain on the fishery. Thus, improving the catch rate of existing pot designs has the potential to significantly improve the profitability of fishing enterprises. In this study, we investigated whether the addition of low-powered purple and white light-emitting diode (LED) fishing lights inside the pots could improve catch rates of snow crab in the Barents Sea. Results showed that pots with purple lights harvested a 12.8% higher catch per unit effort (CPUE; number of crab per pot) of legal-sized crab, which was significantly more than the control pots (p = 0.035); pots with white lights did not catch significantly more crab (p > 0.05). Pots equipped with only light (no bait) caught very few crabs and were not considered a viable alternative. Although purple LEDs increased snow crab capture, the economic benefits of using underwater lights in pots remains unclear given the high capital investment required.publishedVersio

Application of Luminescent Netting in Traps to Improve the Catchability of the Snow Crab Chionoecetes opilio

In this study, we investigated luminescent netting as a means to improve the catch rates of snow crabs Chionoecetes opilio. A laboratory experiment was conducted to investigate the intensity and duration of luminescence using time‐lapse photography. We exposed experimental traps to five different treatments of UV light to excite the luminescent fibers in the netting. Our results showed that luminescent netting can be effectively activated to emit light, and that the resulting intensity and duration of luminescence emitted over time depends on the initial duration of UV exposure and the source of light. A fishing experiment was subsequently conducted in eastern Canada to compare the catch rate of traditional and luminescent traps, and to determine how soak time affected catch rate. Results indicate that the effect of luminescent traps on the CPUE (measured as number of crab per trap) depended on the soak time. The CPUE was significantly higher (a 55% increase) in luminescent traps that underwent relatively short soak times (~1 d), but when soak times were longer (~8 d), the CPUE was not significantly different.publishedVersio

Comparing Catches and Catch Rates by Variable Strength Hooks from Pelagic Longlines to Determine Their Bycatch Reduction Potential for Pilot Whales in the MidAtlantic Bight.

The pelagic longline fishery in the western Atlantic Ocean targeting swordfish (Xiphias gladius) and tunas (Thunnus spp.) historically has a high frequency of interactions with marine mammals, particularly pilot whales (Globicephala spp.) in the Mid-Atlantic Bight (MAB) region. Typical pelagic longline hooks used in the MAB are size 16/0 strong hooks that straighten at 250 lb of pull (113 kg), while alternative weak hooks straighten at 150 lb of pull (68 kg). Taking advantage of the size difference between large bycatch and relatively smaller target species, these weak hooks could be implemented as a bycatch reduction agent. To test this within the tuna fishery of the MAB, 21 sets were made using size 16/0 hooks, targeting yellow fin tuna (Thunnus albacares) and bigeye tuna (T. obesus) alternating strong and weak hooks. To test these hooks in a swordfish targeted area, nine sets were made using larger size 18/0 hooks within the Florida East Coast statistical area (FEC) and the Charleston Bump of the Southern Atlantic Bight statistical area (SAB) alternating strong and weak hooks. Size 18/0 strong hooks straighten at 350 lb (159 kg) of pull, while the weak straightens at 225 lb (102 kg). Results for the tuna targeted sets showed no significant reduction in total catch (a \u3c 0.05) of any target species, with weak hooks having higher trends for catch per unit effort (CPUE) for both tuna and swordfish. The only species to show a significant difference in total catch between strong and weak 16/0 hooks was the pelagic stingray (Pterplatytrygon violacea), with more individuals caught by the strong hook. The 18/0 hook sets had similar catches for all species except the target species swordfish. Swordfish CPUE trended higher for the strong hook, while also having significantly higher total catches. Seven weak hooks were retrieved straightened at haul back; one of these hooks was observed being straightened by a pilot whale at 10m distance from the vessel

Characterization of Swordfish Buoy Gear Catches in the Florida Straits

Swordfish buoy gear (SBG) is a relatively new commercial fishery located off the eastern and southern coasts of Florida that began in 2002. The area targeted by this fishery, part of the Florida East Coast statistical area (FEC), has been closed to commercial pelagic longline gear (PLL) since 2001. Swordfish buoy gear has largely taken the place of PLL as a commercial fishery for swordfish (Xiphias gladius) within the FEC. Conceptually, SBG is similar to a vertical longline, with free-floating individual buoys and “high-flyers” connected to approximately 100 meters of monofilament with one or two hooks constituting one “buoy.” Most vessels currently using this gear are fishing approximately 10 “buoys” simultaneously. Due to the way each individual “buoy” drifts independently with the current, SBG is considered to fish more like PLL than the former NMFS classification of the “handgear” gear type. This study qualitatively compares swordfish catch rates, bycatch rates, and time on hook between contemporary SBG field data and historical PLL observer data from the FEC. Initial analysis shows higher CPUE for SBG vs. PLL (92.2 to 31.8 per 1000 hooks), lower bycatch rates (12.2 to 21.6 per 1000 hooks), and lower average time on hook (2:15 to 6:59). Initial conclusions show that SBG is a cleaner and more efficient commercial fishery for swordfish in this area when compared to PLL

Characterization of Swordfish Buoy Gear Catches in the Florida Straits

Swordfish buoy gear (SBG) is a relatively new commercial fishery located off the eastern and southern coasts of Florida that began in 2002. The area targeted by this fishery has been closed to pelagic longline gear (PLL) since 2001. Swordfish buoy gear has largely taken the place of PLL as a commercial fishery for swordfish (Xiphias gladius) within the FEC. Conceptually, SBG is similar to a vertical longline, with free-floating individual buoys connected to approximately 100 meters of monofilament with one or two hooks constituting one “buoy.” Most vessels currently using this gear are fishing approximately 10 “buoys” simultaneously. Due to the way each individual “buoy” drifts independently with the current, SBG is considered to fish more like PLL than the former NMFS classification of the “handgear” gear type. This study compared swordfish catch and bycatch rates between 56 sets of contemporary SBG field data and historical PLL observer data from the FEC. Catch was dominated by swordfish (91.4%), followed by sharks (6.9%). Analyses show higher swordfish catch-per-unit-effort (CPUE) for SBG vs. PLL (202.4 to 31.8 per 1000 hooks) and much lower bycatch rates for SBG, including no istiophorid billfish, marine mammal, or sea turtle bycatch during the 56 experimental sets. These data indicate that SBG is a cleaner and more efficient commercial fishery for swordfish in this area when compared to PLL. Additional work using small temperature-depth recorders (TDRs) indicate that the actual fishing depths (57.3 m ± 19.2 m) were much shallower than the predicted depths (71.7 m ± 23.7 m). On-going depth modeling work with TDR data is described

Comparing size selectivity of traditional and knotless diamond-mesh codends in the Iceland redfish (Sebastes spp.) fishery

The size selectivity and usability of two diamond mesh codends, a traditional two-panel codend versus an experimental four-panel ultra-cross knotless mesh codend, were compared using the covered codend method in the Iceland redfish (Sebastes norvegicus and S. viviparous) fishery. Results showed that there was no significant difference in size selectivity between the codends at lengths greater than 29 cm for S. norvegicus and 19 cm for S. viviparous. At smaller lengths, size selectivity was undetermined due to small catches at those sizes. For S. norvegicus, both codends demonstrated a high retention ratio (93.4 and 92.9%, respectively) above the minimum reference length (MRL; 33 cm), but also had a high retention below MRL (90.9 and 83.4%, respectively). However, the actual proportion of catch below MRL was low due to few small fish on fishing grounds. Since these fish are difficult to tell apart and have similar morphologies, we investigated the size selectivity of the two codends for both species combined, resulting in similar results of no difference in size selectivity, but a large increase in actual catches below MRL, which were primarily S. viviparous. This study concludes that the experimental codend does not improve the size selectivity or usability in the Iceland redfish fishery and both codends will retain large proportions of undersized fish if present on fishing grounds; however, few undersized fish were present in the study area.acceptedVersio