No abstract

NOTES ABOUT LUTJANUS, ONE OF MAIN COMMODITIES IN CAPTURE FISHERIES. The snapper, genus Lutjanus are commercially important fish species, distributed in tropical to temperate regions all over the world. This group is mostly reef associated marine fishes and several deep-water (>100 m) species. Genus Lutjanus contains the largest number of species, i.e. 72 species in the world and almost 33 species in Indonesian waters. The snappers are dioecious and gonochoristic organisms, this means that they have separate sexes and the sexual differentiation remains constant throughout their life span. They are carnivorous and the diet consist mainly of small fishes, crustaceans, mollucas, and pelagic urochordata. PENDAHULUAN Marga Lutjanus dikenal dengan nama lokal ikan kakap atau snappers dalam bahasa Inggris. Keseluruhan jenis dalam marga ini merupakan sumber daya ikan yang penting, baik secara komersial maupun rekresional. Pada umumnya, ikan kakap dimanfaatkan sebagai ikan konsumsi, dijual dalam bentuk segar atau fillet. Selain itu, jenis ikan ini juga dijadikan sebagai ikan target dalam wisata pancing di beberapa perairan Indonesia.

This study provides information on the reproductive biology of the coral catshark caught in the waters around Seribu Islands, Indonesia. A total of 257 coral catsharks were collected from February 2017 to January 2018. The total length of coral catshark ranged from 170 to 585 mm for females and 255-575 mm for males, respectively. The total weight of females ranged from 85 to 640 g and males from 100 to 620 g The sex ratio between females and males was 0.45 and it was not significantly different from the expected 1:1 ratio. The growth pattern of coral catsharks in Seribu Island was negatively allometric and the population was dominated by mature sharks. The mean size at first maturity was estimated to be 557 mm for females and 514 mm for males, based on to the relationship between the proportion between maturity stage and total length. The ovulation season was estimated occur from October to March, whereas September to April was mating season based on monthly variations of gonadosomatic index (GSI) values and the occurrence of egg cases in uterus.

Study on reproductive aspects of brownstripe red snapper Lutjanus vitta (Quoy & Gainmard, 1824) in Jakarta Bay and its surroundings can obtain important information for fish resources management. The objective of this research is to analyze length frequency distribution, sex ratio, gonadal maturation, gonado somatic index, the length at first maturity (Lm) and the average length of captured (Lc) for this fish. This research was conducted from April 2014 to January 2015 with sampling location in Tanjung Pasir Fishing Port, Tangerang. Fish sampling and of fish that were. The observed aspects included fork length, weight, sex, gonad maturity and gonad weight was done monthly. The result showed that the fork length of this fish ranged between 132-265 mm with the equal sex ratio. The capture fish are dominated by fish with immature stage. The highest of gonado somatic index was on September 2014 (2%). The fork length at first maturity (Lm) were 252 mm (male) and 187 mm (female) while the average fork length of captured (Lc) was 178 mm. This condition can cause a growth overfishing. AbstrakKajian beberapa aspek reproduksi ikan kakap Lutjanus vitta (Quoy & Gainmard, 1824) di Teluk Jakarta dan sekitarnya dapat menghasilkan informasi yang sangat penting dalam rangka pengelolaan sumber daya ikan tersebut. Tujuan pene-litian ini adalah untuk menganalisis sebaran frekuensi panjang, nisbah kelamin, kematangan gonad, indeks kematangan gonad, ukuran kali pertama matang gonad, dan rata-rata panjang tertangkap ikan kakap. Penelitian dilaksanakan pada bulan April 2014 hingga Januari 2015 di Tempat Pelelangan Ikan (TPI) Tanjung Pasir, Tangerang. Aspek yang diamati meliputi panjang cagak dan bobot tubuh ikan, jenis kelamin, kematangan gonad, dan bobot gonad. Hasil penelitian me-nunjukkan bahwa ukuran panjang cagak ikan kakap berkisar antara 132-265 mm dengan nisbah kelamin dalam keadaan seimbang. Ikan kakap yang tertangkap didominasi oleh ikan yang belum matang gonad. Indeks kematangan gonad tertinggi terjadi pada bulan September 2014 yaitu 2%. Ukuran panjang cagak kali pertama ikan matang gonad (Lm) adalah 252 mm (jantan) dan 187 mm (betina), serta panjang cagak rata-rata tertangkap (Lc) adalah 178 mm. Kondisi ini dapat menyebabkan lebih-tangkap yang mengganggu tingkat pertumbuhan ikan kakap.

The elevated extinction risk of elasmobranchs is proportional with the increase of fishing mortality due to overfishing. Indonesia is the biggest shark fishing country in the world, with Tanjung Luar as a fishing village specifically targeting sharks. More than 30 species of sharks and rays that have been landed in Tanjung Luar recently received increased conservation status under the International Union for Conservation of Nature (IUCN). This research aimed to analyze the catch abundance of vulnerable or endangered elasmobranchs in Tanjung Luar and identify the fishing seasons. Four years of landing monitoring data from 2014-2017 were analyzed the fishing seasons and fisheries pattern of vulnerable or endangered elasmobranchs species in Tanjung Luar, calculated Catch per Unit Effort (CPUE) based on fishing power index and also fishing season index. The CPUE of sharks and rays from 2014 to 2017 fluctuated but was not significantly different. We found that shark fishing season occurred in six months and ray fishing season occurred only in four months. The results suggested that management measures should focus on gear control and spatio-temporal closures which could have significant benefits for the conservation of elasmobranch species, and may help to improve the overall sustainability of the fishery.