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

Length-weight and length-length relationships, condition factors and optimal length of some fish species from the Persian Gulf and Oman Sea

Length-weight relationships (LWRs), relative condition factor (Krel), relative weight (Wr) and optimal length (Lopt) were calculated for five important commercial fishes from Iranian waters of the Persian Gulf and Oman Sea. Samples were collected from 2011 and December 2012 in 11 stations in three Iranian provinces (Hormuzgan, Khozestan and Sistan and baluchestan) using trawl and gillnets. Also, length-length relationships (LLRs) for Pampus argenteus and Scomberomorus commerson were computed. The values of the exponent b in the length-weight relationship ranged from 2.593 for S. commerson to 2.995 for P. argenteus. Krel varied between 1.01 ± 0.08 for Parastromateus niger and 1.06 ± 0.41 for P. argenteus. Also, Wr ranged from 59.12 ± 47.74% for S. commerson to 107.78 ± 107.29% for Eleutheronema tetradactylum. The Lopt were calculated for all five species. A negative allometric growth was found in S. commerson, while other four species (E. tetradactylum, Otolithes ruber, P. niger and P. argenteus) had isometric growth. The length-weight and length-length relationships presented here are for the first time in the Iranian coastal waters of the Persian Gulf and Oman Sea, which can provide a basis for fisheries management

The effect of depth variation on size and catch rate of green tiger shrimp, Penaeus semisulcatus (De Haan, 1884) in Bushehr coastal waters, Northern Persian Gulf

Catch data of Penaeus semisulcatus were collected for three years (2009-2011) during the period of June to August to estimate the effect of depth variation on length frequency and catch rate (Kg h-1) of the species. No difference was observed between the shallow and deeper catch rate (ANOVA test, P &gt; 0.05). However, the size composition of green tiger shrimp were affected by depth variation (Kolmogorov-Smirnov test, P &lt; 0.05) and were positively correlated with depth (P &lt; 0.05 and r = 0.140). The smaller individuals prefer shallow waters, indicating behaviour differences between the juveniles and adults of this species. The positive correlation between size of shrimp and water depth can be attributed to the behaviour predation.Keywords: Green tiger shrimp, Penaeus semisulcatus, catch rate, depth variation, Persian GulfAfrican Journal of Biotechnology Vol. 12(20), pp. 3058-306

Effect of hook and bait size on catch efficiency in the Persian Gulf recreational fisheries

The effect of hook and bait sizes on the catch efficiency and size composition of Spangled Emperor Lethrinus nebulosus, Orange‐spotted Grouper Epinephelus coioides, and Narrowbarred Mackerel Scomberomorus commerson was investigated in the recreational and semi‐subsistence handline fishery in the Persian Gulf. Based on expectations that increasing hook and bait sizes would decrease the catch efficiency of the smaller individuals while maintaining the catch efficiency of larger fish, we investigated the effect of increasing hook and bait sizes. For all three species, the results indicated slightly lower catch efficiency for the smaller fish when larger hooks were used. Furthermore, the results demonstrated a significant increase in catch efficiency for the larger sizes of Spangled Emperor and Orange‐spotted Grouper when fished with larger hooks, an effect that increased with fish size for both species. Additionally, the overall catch efficiency did not vary significantly when increasing hook and bait sizes for the three species investigated. This study shows that fishing with larger hooks and larger bait would change the exploitation pattern of these species toward higher proportions of larger fish in the catches. Moreover, based on the size distribution of the species on the fishing grounds during the study period, the use of larger hooks and bait would lead to significant increases in the total number of Spangled Emperor caught (41% increase; 95% confidence interval [CI] = 17–69%) and the total number of Orange‐spotted Grouper caught (151% increase; 95% CI = 132–336%), respectively. The results indicated a similar effect for Narrowbarred Mackerel; however, the effect was far less profound than for the two other species and was not significant for any size‐classes

Study on different hook and bait types in the Persian Gulf hand line fishery: optimization and development

The hand line fishery in the Persian Gulf is considered a sustainable fishing practice. The aims of this study were to estimate catch composition, catch rates, length frequencies, and the percentage of individuals caught below length-at-maturity with two types of hooks, circle and J-style with natural and artificial bait by hand line fishing. Circle and J-style hooks with natural and artificial bait were alternated. Sampling operations were carried out on Qeshm Island, in the North of the Persian Gulf in spring 2015. Catch per unit effort for J-hooks with natural and artificial bait and circle hooks with natural and artificial bait differed significantly (p  0.05). For most species (except L. nebulosus), there was no significant difference between circle and J-style hooks for the proportion of individuals smaller than length-at-maturity (p > 0.05)

Length-weight and length-length relationships, condition factors and optimal length of some fish species from the Persian Gulf and Oman Sea

Length-weight relationships (LWRs), relative condition factor (Krel), relative weight (Wr) and optimal length (Lopt) were calculated for five important commercial fishes from Iranian waters of the Persian Gulf and Oman Sea. Samples were collected from 2011 and December 2012 in 11 stations in three Iranian provinces (Hormuzgan, Khozestan and Sistan and baluchestan) using trawl and gillnets. Also, length-length relationships (LLRs) for Pampus argenteus and Scomberomorus commerson were computed. The values of the exponent b in the length-weight relationship ranged from 2.593 for S. commerson to 2.995 for P. argenteus. Krel varied between 1.01 ± 0.08 for Parastromateus niger and 1.06 ± 0.41 for P. argenteus. Also, Wr ranged from 59.12 ± 47.74% for S. commerson to 107.78 ± 107.29% for Eleutheronema tetradactylum. The Lopt were calculated for all five species. A negative allometric growth was found in S. commerson, while other four species (E. tetradactylum, Otolithes ruber, P. niger and P. argenteus) had isometric growth. The length-weight and length-length relationships presented here are for the first time in the Iranian coastal waters of the Persian Gulf and Oman Sea, which can provide a basis for fisheries management

Size Selectivity of 75 and 90 mm Square Mesh Windows (SMW) Codend for

Square mesh windows (SMWs) with 75 (75SMW; 37.5 mm bar length) and 90 mm (90SMW; 45 mm bar length) nominal mesh size were tested for determining size selectivity in dhow prawn fisheries of the Persian Gulf (Hormuzgan province). Fishing trials were conducted on the commercial fishing grounds of Hormuzgan province of the northern Persian Gulf by commercial dhow trawler. Covered codend methods were utilized for collecting data during October and November 2012. Totally 21 and 16 valid hauls were performed with 75SMW and 90SMW, respectively. The mean L50 values of 75SMW 9 SMW . &plusmn; . .7 &plusmn; . Penaeus merguiensis) .9 &plusmn; . .9 &plusmn; . Jinga shrimp (Metapenaeus affinis) 8. &plusmn; . 8 9. &plusmn; . ork length for Indian ilisha (Ilisha melastoma), and 8. &plusmn; . 8. &plusmn; . k ulphur goatfish (Upeneus sulphurous), respectively. This study clearly shows that there is not any notable different in size selectivity of square mesh windows with different mesh sizes for investigated species. Future studies on different by-catch reduction methods such as full square mesh codends or grids should improve size selectivity of the species and efforts to reduce by-catch in this fishing system.Square mesh windows (SMWs) with 75 (75SMW; 37.5 mm bar length) and 90 mm (90SMW; 45 mm bar length) nominal mesh size were tested for determining size selectivity in dhow prawn fisheries of the Persian Gulf (Hormuzgan province). Fishing trials were conducted on the commercial fishing grounds of Hormuzgan province of the northern Persian Gulf by commercial dhow trawler. Covered codend methods were utilized for collecting data during October and November 2012. Totally 21 and 16 valid hauls were performed with 75SMW and 90SMW, respectively. The mean L50 values of 75SMW 9 SMW . &plusmn; . .7 &plusmn; . Penaeus merguiensis) .9 &plusmn; . .9 &plusmn; . Jinga shrimp (Metapenaeus affinis) 8. &plusmn; . 8 9. &plusmn; . ork length for Indian ilisha (Ilisha melastoma), and 8. &plusmn; . 8. &plusmn; . k ulphur goatfish (Upeneus sulphurous), respectively. This study clearly shows that there is not any notable different in size selectivity of square mesh windows with different mesh sizes for investigated species. Future studies on different by-catch reduction methods such as full square mesh codends or grids should improve size selectivity of the species and efforts to reduce by-catch in this fishing system

Mono-vs multifilament gillnets: effects on selectivity of narrow-barred Spanish mackerel Scomberomorus commerson in the Persian Gulf

Iranian coastal fishers targeting narrow-barred Spanish mackerel (Scomberomorus commerson) recently replaced their historical multifilament gillnets with those made from monofilament, evoking management concerns over potential increases in catch-per-unit-of-effort. During 20 fishing days, we compared catches from replicate surface-set gillnets that were identical in terms of mesh size (140 mm stretched opening), length (180 m), depth (30 m), hanging ratio (0.56) and spatiooral deployment, but had different materials: Multifilament (1.8-mm diameter twisted twine) vs monofilament (0.8-mm diameter twine). Compared with the multifilament gillnet, there was a trend of greater catches (up to 1.3×) of S. commerson and another retained species, mackerel tuna (Euthnus affinis), along with one discarded species, giant catfish (Netuma thalassina) by the monofilament gillnet. However, statistical significance was restricted to E. affinis catches and a bias towards smaller S. commerson. These differences were attributed to species-specific catching mechanisms within gillnet material, with larger S. commerson retained by their teeth in the multifilament and all E. affinis more securely retained by their deeper bodies in the monofilament. Gillnet materials require regulation to preclude excessive effort on fully exploited stocks of species such as S. commerson