The biology of elasmobranchs makes them very vulnerable to fishing pressure and there is increasing international concern over their exploitation. In northern Australia the stocks of some species may be shared with those in southern Indonesia. Indonesia has the highest landings of elasmobranchs worldwide ([100,000 t p.a.) and millions of Indonesian artisanal fishers rely heavily on elasmobranchs taken in target fisheries. They are also taken by industrial trawlers and as bycatch in pelagic tuna fisheries. This paper, resulting from a collaborative project between Australia and Indonesia, summarises the elasmobranch fisheries; the characteristics of the fisheries are outlined, the status of the stocks are assessed, and management options described and discussed. The project focussed on representative markets and fish landing sites in southern Indonesia from 2001 to 2005. Data were from market surveys, the records of the Indonesian Directorate General of Capture Fisheries, and from research cruises. Data from the ongoing tuna monitoring programme showed that shark bycatch from the tuna fleets forms about 11% of shark landings in Indonesia. Yield per recruit and related analyses were used to integrate biological information to indicate the productivity of each species to allow for management policy options and constraints. Research cruise data show that catch rates of elasmobranchs in the Java Sea declined by at least one order of magnitude between 1976 and 1997. The results indicate strongly that many of the shark and ray species in Indonesia are overfished and that the most effective management strategy may need to involve capacity control, such as licencing, gear restrictions and catch limits, together with controls on the fin trade.

Abundance indices based on nominal CPUE do not take into account confounding factors such as fishing strategy and environmental conditions, that can decouple any underlying abundance signal in the catch rate. As such, the assumption that CPUE is proportional to abundance is frequently violated. CPUE standardisation is one of the common analyses applied. The aims of this paper were to provide a statistical modelling framework for conducting CPUE standardisations using the Observer Program data for bigeye tuna, yellowfin tuna, albacore and southern bluefin tuna, and provide a comparison in the trends between the nominal CPUEs and their standardised indices obtained. The CPUE standardisations were conducted on the Observer Program collected between 2005 and 2007, by applying GLM analysis using the Tweedie distribution. The results suggested that year, area, HBF and bait factors significantly influenced the nominal CPUEs for the four tuna species of interest. Some extreme peaks and troughs in the nominal time series were smoothed in the standardised CPUE time series. The high degree of temporal variability that is still shown in the standardised CPUE trends suggests that the data are too sparse to give any meaningful indication of proxy abundance. Nevertheless, this may also suggest that variables used in the GLMs do not sufficiently account for all of the confounding factors, or abundance may indeed be truly variable.

No abstract

ABSTRAKPerairan Kwandang merupakan salah satu basis utama perikanan pelagis kecil di perairan laut Sulawesi. Salah satu jenis yang banyak dimanfaatkan adalah ikan bentong (Selar crumenophthalmus). Penelitian ini bertujuan untuk menduga parameter populasi, tingkat pemanfaatan (E), dan biologi reproduksi dari ikan bentong.. Data panjang cagak dikumpulkan dari PP Kwandang dari bulan Januari hingga November 2012. Pendugaan parameter populasi dilakukan dengan menggunakan metode Bhattacharya dengan bantuan software FISAT II Hasil analisis menunjukkan bahwa laju pertumbuhan (K) sebesar 0,76 per tahun dengan L"=24,7 cm. Laju kematian total (Z) sebesar 2,63 per tahun, dengan laju kematian alamiah (M) sebesar 1,28 per tahun, laju kematian akibat penangkapan (F) sebesar 1,3 per tahun dan laju pemanfaatan 0,51. Tingkat pemanfaatan ikan bentong sudah relatif optimum. Rasio jenis kelamin ikan bentong jantan dan betina adalah 1: 1,02. TKG I paling banyak ditemukan. Musim pemijahan ikan bentong diduga terjadi pada bulan November dan Desember. Kata Kunci : Ikan bentong, parameter populasi, biologi, Kwandang ABSTRACT

Studies on artisanal shark fisheries in Tanjungluar - East Lombok were conducted during the year 2001-2011 (except in 2003 and 2007). A sampling method called “rapid market survey” method was employed to collect catch data from surface and bottom longlines fishing, rapidly. Biological data and fisheries data were collected during survey. Catch data for shark were also obtained from daily records filled by TPI officers in Tanjungluar between 2009 and 2010. The results showed that shark<br />longline fishing was conducted every month. The trend of shark catches relates to the number of fishing vessels, fishing ground, and weather conditions at sea. The period between July and September is a transitional season from East to West seasons. During this season, the wind strength is weakened and a good fishing season for the fishers. The lowest catch occurs in January (1.06 tonnes) and the highest catch in September with the total catch of 24.6 tonnes. Sharks caught by surface longline were dominated by Silky shark, Carcharhinus falciformis (40-90%) with the size range of 100-125 cm. The catch of bottom longline was mostly consisting of fish in mature condition that dominated by Grey reef shark (<em>Carcharhinus amblyrhynchos</em>), Common black tip shark (<em>C. limbatus</em>), Spot tail shark (<em>C. sorrah</em>), and Scalloped hammerhead shark (<em>Sphyrna lewini</em>), with the size range of 125-200 cm, 170- 250 cm, 100-150 cm, and 170-300 cm, respectively. Surface longline fishing occurs in the offshore waters in depth more than 200 m to 3000 m, whereas bottom longline fishing is operated at a depth of 50-100 m around islands.

No abstract

No abstract

(P.T. Perikanan Samodra Besar) data are a valuable source, since they are the longest time series of catch and effort data available from the fishery. This paper aimed to interpret the spatial and temporal catch and effort trends to the extent possible and to reconcile apparent changes in targeting practices against the actual catch. Catch and effort data collected by P.T. Perikanan Samodra Besar from its Benoa-based longliners during 1978-1995 were summed to obtain annual catch, effort, and catch per unit of effort trends. To generate spatial distributions of catch and effort, catch and effort data were aggregated by 5-degree squares. The data showed that P.T. Perikanan Samodra Besar vessels commenced deep longlining in 1983, i.e. 56% of the total sets in 1983 using 10 or more hooks between floats. Prior to that, P.T. Perikanan Samodra Besar vessels used 6 hooks between floats,which resulted in a larger amount of yellowfin tuna (Thunnus albacares) as well as overall tuna catch. However, bigeye tuna (Thunnus obsesus) catch per unit of effort only increased from 1992. The increase in big eye tuna catch per unit of effort coincided with a reduced fishing range and concentration within an area where P.T. Perikanan Samodra Besar had not previously experienced high big eye tuna catches, as opposed to focusing their effort on areas where they had historically caught big eye tuna. In the absence of supplementary information, and assuming that the switch to deep longlining in 1983 was done to target big eye tuna, the analysis suggests that the outcome of P.T. Perikanan Samodra Besar fishing activities between 1983 and 1991 were inconsistent with their objectives.