Species composition and biology reproductions aspects of stingray (Batoidea) in south coast of Prigi waters, Trenggalek, East Java, Indonesia

Abstract

Stingray (Batoidea) are often caught as bycatch in south coast of Prigi waters. The stingray resource has very limited in number and require a long time to reproduce. Attention must be paid to avoid the extinct of stingray resource. This research aimed to justify species composition and identify length weight relationship, sex ratio, and clasper maturity level of stingray (Batoidea) caught in south coast of Prigi waters. The research was carried out from December 2019 to April 2020 at Prigi archipelago fishing port as landing place. This study used a quantitative descriptive method with the number of samples that were successfully obtained as many as 97 stingray. During the study, 6 species of stingray (Batoidea) were identified, namely Taiwan guitarfish (Rhinobatos schlegelii), blotched fantail stingray (Taeniurops meyeni), Japanese devilray (Mobula japanica), bluespotted maskray (Neotrygon kuhlii), shark ray (Rhina ancylostoma), dan bluespotted fantail ray (Taeniura lymma). Result indicated that Taiwan guitarfish (R. schlegelii) and bluespotted maskray (N. kuhlii) were two dominant stingray species in south coast of Prigi waters with proportion of 47.42% and 41.24% respectively. Disk width (Dw) and weight (W) of Taiwan guitarfish (R. schlegelii) ranged from 15.2 cm to 24.6 cm and from 268 gr to 1060 gr respectively and bluespotted maskray (N. kuhlii) ranged from 17.3 cm to 39.3 cm and from 140 gr to 2006 gr respectively. Another analysis showed that Taiwan guitarfish (R. schlegelii) and bluespotted maskray (N. kuhlii) had length weight relationship equations W = 0.0202 Dw34699 and W=0.0351*Dw29848 respectively. The sex ratio of Taiwan guitarfish Taiwan guitarfish (R. schlegelii) dan bluespotted maskray (N. kuhlii) was 1:1.4 and 1:1.2 respectively. In addition, clasper maturity level of the Taiwan guitarfish (R. schlegelii) and bluespotted maskray (N. kuhlii) species was dominated by Non-Calcification (NC). In conclusion, The stingray (Batoidea) caught in south coast of Prigi waters were dominated by Taiwan guitarfish (R. schlegelii) and bluespotted maskray (N. kuhlii). Length weight relationship of Taiwan guitarfish (R. schlegelii) and bluespotted maskray (N. kuhlii) was allometric positive and isometric respectively. Both of them was in balance condition sex ratio and was dominated by immature stage. Hence fishing activities in south coast of Prigi waters should avoid the stingray as bycatch in order to preserve the stock.

Life history (length-weight relationship, conditional factors, reproductive aspects), stomach contents and nursery ground of stingray in the Arafura Sea

“…The sex ratio is a representation of the ability to recruit in a fauna population. Some authors state that the balanced sex ratio describes the population's ability to maintain good recruitment [13] and [35]. In studies of different sex ratios between species of stingrays, this is in accordance with several previous research results [35] and [36].…”

“…Some authors state that the balanced sex ratio describes the population's ability to maintain good recruitment [13] and [35]. In studies of different sex ratios between species of stingrays, this is in accordance with several previous research results [35] and [36]. Several factors can affect the sex ratio are; overfishing in one sex due to differences migration [36], selectivity of fishing gear, growth rate and environment [36], selectivity of fishing gear, growth speed and environment.…”

Sustainable economic analysis and length weight relationship of Bullet Tuna (Auxis rochei) fishery in east area of Bali Strait, Indonesia

“…To test the value of b = 3 or b 3, a t-test (partial test) was carried out (Bintoro et al 2021d).with the hypothesis: H0: b = 3, the growth pattern is isometric, which means that the length and weight relationship is balanced.…”

Growth and exploitation rate of Dwarf Whipray (Brevitrygon heterura) landed from Tanjung Beringin, Serdang Bedagai Regency, North Sumatera Province

“…This shows that the dwarf whipray has a negative allometric growth pattern, namely the growth in length is greater than the growth in weight. According to [12], the growth pattern is divided into two, namely isometric and allometric. It is said to be isometric if the value of b = 3 where the weight growth pattern is proportional to the length growth pattern.…”