Research papers Environmental factors influencing the recruitment and catch of tropical Panulirus lobsters in southern Java, Indonesia David A. Milton a,n , Fayakun Satria b , Craig H. Proctor c , Andhika P. Prasetyo b , Andria A. Utama b , Mohamed Fauzi d a CSIRO Marine and Atmospheric Research, PO Box 2583, Brisbane 4001, Qld Australia b Research Centre for Fisheries Management and Conservation, Jl Pasir Putih, I, Ancol Timur, 14430 Jakarta Utara, Indonesia c CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart 7001, Tasmania, Australia d Research Institute for Marine Fisheries, Muara Baru, Jakarta Utara, Indonesia article info Article history: Received 21 March 2014 Received in revised form 17 September 2014 Accepted 20 September 2014 Available online 30 September 2014 Keywords: Open-access fishery Monsoon Connie2 Panulirus homarus Panulirus penicillatus abstract Tropical Panulirus lobster fisheries in many parts of the world are open-access and poorly-regulated. This is in part because tropical Panulirus lobsters have an extended pelagic larval phase (up to 9 months) and their larval settlement may take place in different habitats and depths. When recruits of a fishery are believed not spawned locally, regulatory incentives are weak. We assessed the potential sources of recruits to a small, valuable fishery for six species of Panulirus lobster in southern Java, Indonesia with a larval advection model. The model predicted that between 1993 and 2007, 50–90% of the recruits were sourced locally compared to a mean of 25% from remote locations. The relative intensity of the Indonesian flow-through, the south Java current and seasonal onshore winds appear to be important in the local retention of recruits. Local fisheries records showed a strong seasonality in catch that we compared to potential environmental triggers with boosted regression trees. We found that the increased catch was associated with the rapid onset of increased rainfall ( 490 mm) at the start of the monsoon (November–May). Fishers believe the coastal runoff during periods of high rainfall increases turbidity and thus enhanced catchability. Catches declined dramatically during an extended monsoon in 2010–2011, but recovered in early 2012 when rainfall patterns became more seasonal. These combined results show that there may be potential benefit of implementing local fisheries management regulations to increase sustainability. However, their effectiveness may be difficult to detect due to the strong influence of climate and oceanographic variability on both recruitment and subsequent catch. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction Management of tropical rock lobster (Panulirus species) fish- eries in less developed countries is challenging. Tropical lobsters have a complex life cycle with an extended pelagic larval phase ( 46 mo: Phillips et al., 2006) and post-settlement phases that occupy different habitats and depths (Haywood and Kenyon, 2009). The long larval phase means that larvae can potentially disperse long distances from their natal reefs. During this extended larval phase, they are exposed to a range of environ- mental conditions that affect their survival and subsequent recruitment (Caputi et al., 2001). This makes managing fisheries of these species especially challenging when the appropriate spatial scale of management is unclear (Lipcius et al., 2001; Butler et al., 2011). The tropical rock lobster fishery throughout Indonesia is a high-value export-oriented open-access artisanal fishery ( 4US $150 M: Anonymous, 2007) that occurs throughout the country. It catches up to six species of Panulirus and several Scyllarids, with the most important species varying regionally. Southern Java is one of the more productive regions, contributing up to 10% of the national catch (Anonymous, 2007). The fishery in southern Java is unusual as it has two sectors. A tangle trap (krendet) sector undertaken by part-time artisanal fishers from coastal cliffs and an inshore bottom gillnet sector that operates from small ( o10 m) vessels. The fishery catches six species of Panulirus, with the majority being Panulirus homarus and Panulirus penicillatus (Milton et al., 2012). Each sector catches different proportions of each species, with the inshore krendets catching mostly the reef- dwelling P. penicillatus. The gillnet sector fishes in deeper water (25–100 m) and mostly catches P. homarus, with some P. versicolor and P. longipes. There is minimal management of the fishery, although catch data are collected from gillnet fishers who sell their catch at government fish auction centres. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/csr Continental Shelf Research http://dx.doi.org/10.1016/j.csr.2014.09.011 0278-4343/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author. E-mail address: david.milton@csiro.au (D.A. Milton). Continental Shelf Research 91 (2014) 247–255