Elasmobranch bycatch by prawn trawls in the Gulf of California: First comprehensive analysis and the effect of fish escape devices

Garcés-García, Karla C.; Tovar-Ávila, Javier; Vargas-Trejo, Bibiana; Chávez-Arrenquín, Darío A.; Walker, Terence I.; Day, Robert W.

doi:10.1016/j.fishres.2020.105639

Cited by 9 publications

(9 citation statements)

References 21 publications

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“…The use of the devices vary and can be configured to suit a specific fishery (Duarte, Broadhurst & Dumont, 2019). For example, the use of a combination of TED and BRD has proven to be effective in minimizing the catch of skates in Suriname, South America (Willems et al, 2016), and Fish Escape Devices, a form of BRD, used in the Gulf of California restricted the capture of mid-sized rays and sharks (Garcés-García et al, 2020). Studies in Australia have shown that, although the capture of smaller individuals remains high (Stobutzki et al, 2002), TEDs are successful at reducing the capture of large elasmobranchs (Brewer et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Ecological risk assessment of elasmobranchs caught in the Gulf of Papua prawn fishery

Baje

Chin

White

et al. 2021

Aquatic Conservation

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1. One-third of all elasmobranch species currently known to occur in Papua New Guinea are taken as bycatch in the Gulf of Papua trawl fishery. An ecological risk assessment was conducted on the 16 species of sharks and 23 species of rays caught by the fishery.2. Eight species were classified to be at low risk, 28 species were at medium risk while three species -Rhynchobatus palpebratus (eyebrow wedgefish), Carcharhinus coatesi (Australian blackspot shark) and Maculabatis astra (blackspotted whipray), all endemic to New Guinea and northern Australiafaced the highest level of risk from the fishery at current fishing levels.3. There is potential for more vessels to enter the fishery in future, which is likely to elevate the risk for a greater proportion of elasmobranch species.Ongoing monitoring of bycatch levels, supported by biological and ecological studies on frequently caught species, is required to assess and manage risk in the future.4. The development and use of trawl excluder devices or bycatch reduction devices in this fishery have the potential to reduce bycatch levels and reduce risk levels.

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Section: Discussionmentioning

confidence: 99%

Ecological risk assessment of elasmobranchs caught in the Gulf of Papua prawn fishery

Baje

Chin

White

et al. 2021

Aquatic Conservation

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“…The maturity stage was assigned to each individual based on the macroscopic inspection of the reproductive structures: primarily ovary development confirmed by the uterus and oviducal gland condition for the females; and clasper rigidity stage confirmed by testis development for males (Garcés‐García et al, 2020; Walker, 2005b) (Table 1). The size at sexual maturity (disc width at which 50% of the individuals in the population are sexually mature, DW 50 ) was estimated for each sex from the proportion of immature and mature individuals at each class interval, using the Gompertz model (asymmetric and non‐logistic curve) and the Brouwer and Griffiths model (symmetric logistic curve), avoiding the use of redundant models (Burnham & Anderson, 2002; García‐Rodríguez et al, 2020; Katsanevakis, 2006).…”

Section: Methodsmentioning

confidence: 99%

“…The spotted round ray Urobatis maculatus Garman 1913 and the thorny stingray Urotrygon rogersi are species with no commercial value in Mexico but are commonly caught as by‐catch by the shrimp trawl fisheries (Garcés‐García et al, 2020; Herrera‐Valdivia et al, 2016; López‐Martínez et al, 2010; Rábago‐Quiroz et al, 2012). According to the IUCN's Red List, U. maculatus is classified as a “Least Concern” species due to its small size, reaching sexual maturity at a smaller length and early age, and being relatively productive (Pollom et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Size at sexual maturity, seasonal variation by maturity stages, and fecundity of the spotted round ray (Urobatis maculatus) and the thorny stingray (Urotrygon rogersi) from the northern tropical eastern Pacific

García‐Rodríguez,

Tovar‐Ávila,

Arellano‐Cuenca

et al. 2024

Journal of Fish Biology

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Round rays (family: Urotrygonidae) are commonly caught as by‐catch by shrimp trawl fisheries in the tropical eastern Pacific (TEP). However, little information on their life history and catch species composition exists for most round ray species, preventing the evaluation of the impact of fishing on their populations. The mean size at sexual maturity (DW50), seasonal variation by maturity stages, and fecundity for two round ray species caught during shrimp trawl research cruises in the south‐eastern Gulf of California (northern TEP) were estimated using a multi‐model approach and inference for the first time, to determine the part of the population of each species that is being affected by shrimp trawling. Disc width (DW) ranged from 7.0 to 30.9 cm for the spotted round ray (Urobatis maculatus), and 7.2–33.5 cm for the thorny stingray (Urotrygon rogersi), with females reaching larger sizes than males in both species. The DW50 was estimated at 12.8 and 11.8 cm DW for the males and females of U. maculatus, respectively, whereas for U.rogersi, it was 15.0 and 18.4 cm DW for males and females, respectively. Embryos were found in females ≥14.5 cm DW in both species. The maximum fecundity was five embryos for U. maculatus (mean = 3.1 ± 0.2 S.E., mode = 4), and six embryos for U. rogersi (mean = 3.0 ± 0.3 S.E., mode = 2). Fecundity and embryo size did not vary with maternal size. Male and female immature and mature individuals for both species, including pregnant females, were found in the catches in all seasons of the year. Our results can help determine the vulnerability of the studied species populations to fishing pressure from shrimp trawling in the northern TEP and guide the development of future monitoring strategies and conservation actions for these species, if necessary.

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“…Unfortunately, studies on modifying traditional fishing gear to reduce negative impacts on biodiversity and stock availability are still lacking (Nofrizal et al, 2018). Studies on tool modification to reduce bycatch have focused on modern and large-scale fishing gear such as trawls (McHugh et al, 2017;Garcés-García, 2020). Several previous studies suggest that efforts to reduce bycatch are by modifying certain parts of the fishing gear bag or adding a means to separate bycatch from the main catch during the fishing process.…”

Section: Introductionmentioning

confidence: 99%

Modification of togok (tidal trap) for reducing bycatch by using BRD vent

Nofrizal¹,

Mauliddin

Jhonnerie³

2022

Depik

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One effort to reduce bycatch in togok is to modify the togok by creating a vent to reduce bycatch by BRD. The BRD installed on the togok was a rope BRD vent made of Polyethelene (PE) with a diameter of 2 mm. The rope BRD vent is attached to the top of the cod-end as an escape vent 25 x 50 cm. The escape vent and the stash cod-end are covered with a net with a mesh size of 5 mm. The cover net aims to collect data on fish catches that pass through the rope BRD vent. The percentage of fish that pass through the rope BRD vent can be calculated, and measure the size of the fish caught in the cod-end and covered as an indicator of the effectiveness of the rope BRD vent on togok. This experiment was carried out for 20 days of fishing operation and 40 hauls. The results showed that the catch of togok without rope BRD vent (conventional) and togok with modified rope BRD vent were different (p 0.05), where the catch of conventional togok was 468.34 kg, and the catch of modified togok was 305.235 kg. The fishing catches in the cod end and cover sections the most are bycatch with 51% and 54% of the percentage of the total catch, and the least in the cod end is the discarded catch, which is 21% of the percentage of the total catch and on the cover is the main catch (main catch) with 19% of the percentage of the total catch.The average size of the catch of togok species of fish is there are many immature sizes, and the average size of the catch of togok species of shrimp is there are in maturity size.Keywords:BycatchBycatch excluder device (BRD)DiscardMain catch

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Elasmobranch bycatch by prawn trawls in the Gulf of California: First comprehensive analysis and the effect of fish escape devices

Cited by 9 publications

References 21 publications

Ecological risk assessment of elasmobranchs caught in the Gulf of Papua prawn fishery

Ecological risk assessment of elasmobranchs caught in the Gulf of Papua prawn fishery

Size at sexual maturity, seasonal variation by maturity stages, and fecundity of the spotted round ray (Urobatis maculatus) and the thorny stingray (Urotrygon rogersi) from the northern tropical eastern Pacific

Modification of togok (tidal trap) for reducing bycatch by using BRD vent

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