Age, sex ratio, length-weight relationships and reproductive biology of Mediterranean swordfish, Xiphias gladius L., 1758, in the eastern Mediterranean

Aliçli, Tuğrul; Oray, I. K.; Karakulak, F. Saadet; Kahraman, Abdullah

doi:10.5897/ajb11.2189

Cited by 6 publications

(3 citation statements)

References 13 publications

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“…2/1, SÜR-KOOP, 2008). and in the eastern Mediterranean and also Aegean Sea, catch-at-sizes of swordfish were ranged from 98.0 to 295.0 cm (Artüz, 1963), 87.6 to 206.7 cm (Tsimenides and Tserpes, 1989), 62.0 to 205.0 cm (Tserpes and Tsimenides, 1995), 51.0 to 74.0 cm (Megalofonou et al, 1995),25.0 to 135.0 cm (De Metrio et al, 1997), 52.5 to 219.0 cm (Alıçlı and Oray, 2001), 67.5 to176.0 cm (Alıçlı, 2008), 60.0 to 240.0 cm (Ceyhan and Akyol, 2009), 60.0 to 172.0 cm (Akyol and Ceyhan, 2011), 87.0 to 188.5 cm (Alıçlı et al, 2012) and 51.0 and 242.0 cm (Akyol and Ceyhan, 2013). In this study all samples were below MLS (54.4-106.8 cm).…”

Section: Discussionmentioning

confidence: 99%

A Comparison of Alternative Circle Hook (Kahle Hook) and J Style Hook Performance in Experimental Pelagic Longline Fishery in Turkey

Özgül¹,

Ulaş²,

Lök³

et al. 2015

Turkish Journal of Fisheries and Aquatic Sciences

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In recent years, circle hooks have been encouraged as an alternative to traditional J-hooks in pelagic longline fisheries to minimize by-catch mortality and injury to sea turtles and other marine wildlife. Prior to this study, circle hooks had not been used by domestic commercial pelagic longliners in Turkey. The main objective of the study was to evaluate the efficiency of kahle hook comparing with J-style hook baited with sardine (Sardina pilchardus) in pelagic longline fishery in the Aegean coast of Turkey (Kuşadası Bay).We used conventional J-style hooks (Mustad 2315DT-4/0) and kahle hooks (Eagle Claw142A-6/0) for each fishing operation and compared catch rates, catch compositions of target and non-target species. The relative performance of kahle and traditional J-style hooks was tested during 22 valid pelagic longline fishing operations between August 2010 and December 2012. A total of 2200 hooks were used equally amongkahle and J-style hooks consecutively. Captured fish were identified, total and fork lengths were measured,weighed, the time of haulback, and hook type as well as by-catch fish were recorded. A total of 78 fish were caught belonging to 13 species during the samplings. The overall CPUE was 4.73 fishes per 100 hooks for kahle hooks and 2.46 fishes for J-style hooks. For the CPUE of all fishes, the difference was statistically significant (Z = -1.977; P<0.05), in favour of the kahle hook being almost two times greater than the J-style hook. Likewise CPUE was 17007.69 g per 100 hooks for kahle style hooks and 4807.27 g for J-style hooks (Z = -1.997; P<0.05). While no difference was found between two hook models on by-catch species, kahle hooks were more efficient in comparison to J hooks on discard species. Swordfish (Xiphiasgladius) had the highest CPUE (2.82) among all species for kahle hooks followed by silver scabbard fish (Lepidopuscaudatus), 0.64. For J-style hooks, silver scabbard fish catch had the highest CPUE (0.64) followed by swordfish (0.55).

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Section: Discussionmentioning

confidence: 99%

A Comparison of Alternative Circle Hook (Kahle Hook) and J Style Hook Performance in Experimental Pelagic Longline Fishery in Turkey

Özgül¹,

Ulaş²,

Lök³

et al. 2015

Turkish Journal of Fisheries and Aquatic Sciences

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“…Spawning in the North Atlantic occurs throughout the year with a peak from April to September in the Caribbean, the Gulf of Mexico and off Florida (Taylor and Murphy, 1992). In the central north Pacific spawning occurs in spring and summer (March through to July), during June to September in the Mediterranean (De Metrio and Megalofonou, 1987;Orsi Relini et al, 1999;Tserpes et al, 2008Alıçlı et al, 2012, in spring (September to December) in the western south Pacific and all year round in equatorial Pacific waters (Nakamura, 1985). Earlier reports suggest that swordfish spawn in warm, relatively close to coastal waters in the western parts of ocean basins (Taylor and Murphy, 1992;Arocha and Lee, 1995).…”

Section: Discussionmentioning

confidence: 99%

Biological Aspects of Swordfish, Xiphias gladius Linnaeus, 1758, Caught During Tuna Longline Survey in the Indian Seas

Varghese,

Vijayakumaran,

Anrose

et al. 2013

Turkish Journal of Fisheries and Aquatic Sciences

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Distribution, abundance and biology of swordfish, Xiphias gladius, of the Indian seas were investigated by analyzing the data gathered during tuna longline surveys conducted by the Fishery Survey of India (FSI). Study undertaken during the period from 2004 to 2010 revealed swordfish Catch Per Unit Effort of 0.02 numbers in 100 hooks from the Arabian Sea; 0.01 from Bay of Bengal and 0.02 form the Andaman and Nicobar waters. About 16% of the specimens caught were juveniles and the sex ratio of smaller fishes was in favour of males, whereas, larger specimens were mostly females. Length-weight relationship established indicated slightly positive allometric growth of the species and length based models revealed difference in growth between sexes. The growth parameters estimated for females were: asymptotic length (L∞) = 311.11 cm, growth coefficient (K) = 0.17/yr and age at zero length (t0) = –0.53 yr, whereas, the growth parameters estimated for males were: L∞ = 243.79 cm, K = 0.22/yr and t0 = –0.37 yr. Diet was dominated by finfishes and cephalopods, while crustaceans were recorded rarely. Sthenoteuthis oualaniensis was the dominant prey species, followed by Paralepis sp. Spawning area was identified in the Lakshadweep waters from where mature females with hydrated oocytes were caught during December to April. Size at 50% maturity for females was estimated at 164.03 cm, which is reached at about four years of age. Mean batch fecundity was 4.5 million, while the relative fecundity was 37.5 hydrated oocytes per gram of body weight and the diameters of mature oocytes were in the range of 0.9-1.6 mm. Our results provide preliminary information on the abundance, growth and biology of this species in the Indian seas which should be useful to fishery managers.

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“…Despite previous studies that investigated swordfish reproduction in the Mediterranean Sea (Alıçlı, Oray, Karakulak, & Kahraman, 2012;Corriero, Acone, Desantis, & Zubani, 2004;Corriero et al, 2007;de la Serna et al, 1996;Macías, Hattour, Serna, & Godoy, 2005;Megalofonou, Dean, De Metrio, Wilson, & Berkeley, 1995), comprehensive information on the reproductive strategies and spawning areas are far from being firmly established.…”

Section: Introductionmentioning

confidence: 98%

Maturity assignment based on histology‐validated macroscopic criteria: Tackling the stock decline of the Mediterranean swordfish (Xiphias gladius)

Marisaldi

Basili

Candelma

et al. 2019

Aquatic Conservation

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Effective stock assessment relies on the evaluation of the reproductive potential of a population, but this is often achieved using fast, inexpensive, and inaccurate macroscopic indicators of gonadal maturity. Indeed, this approach suffers from high error rates as a result of misclassification and operator errors. Although histology is considered the gold standard to assign reproductive stages, it represents a time‐consuming and expensive method. Therefore, cost‐effective approaches are currently needed to assess the species‐specific reproductive potential and define the correct size at first maturity (L50). In the present study a histology‐calibrated method based on the gonadal index (GI) was developed to assign maturity stages to the overfished Mediterranean swordfish (Xiphias gladius), supported by histological classification of gonadal development, an estimation of L50, and an analysis of the reproductive output of this species. The performance of this new method had an overall agreement of 90% with histological data, and the L50 calculated by the GI‐based method compared with histology analysis was not statistically different (p > 0.05). Moreover, in order to apply this method without bias, a thorough validation of the relationship between length and gonad weight was carried out and the suitability of the GI to compare individuals of different size and maturity stages was confirmed. The present findings provide a comprehensive picture of the patterns characterizing Mediterranean swordfish reproduction and a promising method to assign maturity stages based on a macroscopic indicator. This method has the potential to be extensively applied during routine fish sampling activities in the field because of its simple requirements.

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Age, sex ratio, length-weight relationships and reproductive biology of Mediterranean swordfish, Xiphias gladius L., 1758, in the eastern Mediterranean

Cited by 6 publications

References 13 publications

A Comparison of Alternative Circle Hook (Kahle Hook) and J Style Hook Performance in Experimental Pelagic Longline Fishery in Turkey

A Comparison of Alternative Circle Hook (Kahle Hook) and J Style Hook Performance in Experimental Pelagic Longline Fishery in Turkey

Biological Aspects of Swordfish, Xiphias gladius Linnaeus, 1758, Caught During Tuna Longline Survey in the Indian Seas

Maturity assignment based on histology‐validated macroscopic criteria: Tackling the stock decline of the Mediterranean swordfish (Xiphias gladius)

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