Retention properties of the Agulhas bank and their relevance to the chokka squid life cycle

Retention is thought to be a crucial component required create favourable habitat for coastal pelagic species. It vital the survival of ‘chokka’ squid (Loligo reynaudii), which fishery that supports thousands people living in Eastern Cape South Africa. After chokka spawn, retention on Agulhas Bank prevent starvation early life stages. Using high-resolution ocean model, this study quantifies properties most relevant squid. We estimate proportion virtual Lagrangian particles, representing paralarvae, are retained within 30 days after being released from main spawning sites. Over an 18-year period (1995–2013), considerable variability found seasonal and interannual timescales, with greatest occurring particles further west. The greater losses easternmost release sites due increased interaction Current. While 90–100% common scenario, high loss (>50%) events also apparent associated different modes These include i) meanders cause offshore flow at northeast edge Bank, ii) presence fast, onshore branch Current rapidly advecting off west (associated Natal Pulse) iii) positioned south leading eastern Bank. third mode usually occurs 1–2 months passage Pulse or meander. However, weeks Pulse, increases, so timing these relative particle crucial. This shows key understanding paralarvae lies both occurrence dynamic features their events.