Martins, RSRoberts, MJLett, CChang, NicoletteMoloney, CLCamargo, MGVidal, EAG2014-06-172014-06-172013-08Martins, R.S., Roberts, M.J., Lett, C., Chang, N., Moloney, C.L., Camargo, M.G. and Vidal, E.A.G. 2013. Modelling transport of chokka squid (Loligo reynaudii) paralarvae off South Africa: reviewing, testing and extending the ‘Westward Transport Hypothesis' Fisheries Oceanography, vol. 23(2), pp 116-1311054-6006http://onlinelibrary.wiley.com/doi/10.1111/fog.12046/pdfhttp://hdl.handle.net/10204/7467Copyright: 2013 John Wiley & Sons Ltd. This is the pre/post print. The definitive version is published in Fisheries Oceanography, vol. 23(2), pp 116-131Annual landings of chokka squid (Loligo reynaudii), an important fishing resource for South Africa, fluctuate greatly, and are believed to be related to recruitment success. The ‘Westward Transport Hypothesis’ (WTH) attributes recruitment strength to variability in transport of newly hatched paralarvae from spawning grounds to the ‘cold ridge’ nursery region some 100–200 km to the west, where oceanographic conditions sustain high productivity. We used an individual-based model (IBM) coupled with a 3-D hydrodynamic model (ROMS) to test the WTH and assessed four factors that might influence successful transport – Release Area, Month, Specific Gravity (body density) and Diel Vertical Migration (DVM) – in numerical experiments that estimated successful transport of squid paralarvae to the cold ridge. A multifactor ANOVA was used to identify the primary determinants of transport success in the various experimental simulations. Among these, release area was found to be the most important, implying that adult spawning behaviour (i.e., birth site fidelity) may be more important than paralarval behaviour in determining paralarval transport variability. However, specific gravity and DVM were found to play a role by retaining paralarvae on the shelf and optimizing early transport, respectively. Upwelling events seem to facilitate transport by moving paralarvae higher in the water column and thus exposing them to faster surface currents.enAgulhas BankChokka squidLarval transportParalarvaeWestward Transport HypothesisArticleMartins, R., Roberts, M., Lett, C., Chang, N., Moloney, C., Camargo, M., & Vidal, E. (2013). Modelling transport of chokka squid (Loligo reynaudii) paralarvae off South Africa: reviewing, testing and extending the ‘Westward Transport Hypothesis'. http://hdl.handle.net/10204/7467Martins, RS, MJ Roberts, C Lett, Nicolette Chang, CL Moloney, MG Camargo, and EAG Vidal "Modelling transport of chokka squid (Loligo reynaudii) paralarvae off South Africa: reviewing, testing and extending the ‘Westward Transport Hypothesis'." (2013) http://hdl.handle.net/10204/7467Martins R, Roberts M, Lett C, Chang N, Moloney C, Camargo M, et al. Modelling transport of chokka squid (Loligo reynaudii) paralarvae off South Africa: reviewing, testing and extending the ‘Westward Transport Hypothesis'. 2013; http://hdl.handle.net/10204/7467.TY - Article AU - Martins, RS AU - Roberts, MJ AU - Lett, C AU - Chang, Nicolette AU - Moloney, CL AU - Camargo, MG AU - Vidal, EAG AB - Annual landings of chokka squid (Loligo reynaudii), an important fishing resource for South Africa, fluctuate greatly, and are believed to be related to recruitment success. The ‘Westward Transport Hypothesis’ (WTH) attributes recruitment strength to variability in transport of newly hatched paralarvae from spawning grounds to the ‘cold ridge’ nursery region some 100–200 km to the west, where oceanographic conditions sustain high productivity. We used an individual-based model (IBM) coupled with a 3-D hydrodynamic model (ROMS) to test the WTH and assessed four factors that might influence successful transport – Release Area, Month, Specific Gravity (body density) and Diel Vertical Migration (DVM) – in numerical experiments that estimated successful transport of squid paralarvae to the cold ridge. A multifactor ANOVA was used to identify the primary determinants of transport success in the various experimental simulations. Among these, release area was found to be the most important, implying that adult spawning behaviour (i.e., birth site fidelity) may be more important than paralarval behaviour in determining paralarval transport variability. However, specific gravity and DVM were found to play a role by retaining paralarvae on the shelf and optimizing early transport, respectively. Upwelling events seem to facilitate transport by moving paralarvae higher in the water column and thus exposing them to faster surface currents. DA - 2013-08 DB - ResearchSpace DP - CSIR KW - Agulhas Bank KW - Chokka squid KW - Larval transport KW - Paralarvae KW - Westward Transport Hypothesis LK - https://researchspace.csir.co.za PY - 2013 SM - 1054-6006 T1 - Modelling transport of chokka squid (Loligo reynaudii) paralarvae off South Africa: reviewing, testing and extending the ‘Westward Transport Hypothesis' TI - Modelling transport of chokka squid (Loligo reynaudii) paralarvae off South Africa: reviewing, testing and extending the ‘Westward Transport Hypothesis' UR - http://hdl.handle.net/10204/7467 ER -