Warmer sea threat to fish stocks
Scientists from the CSIRO and WA's Fisheries Department are studying the effects of abnormal ocean temperatures amid evidence they are playing havoc with fish stocks.
Almost four years after waters off the State's west coast were hit by an "unprecedented" heatwave that devastated some fisheries, there are signs marine temperatures could again be above average this summer.
Further cuts to bag limits for popular recreational fishing species, such as herring and abalone, are understood to be on the cards because of the situation.
Ming Feng, a leading oceanographer from the CSIRO, said the latest data indicated local sea temperatures were about half a degree warmer than normal for this time of the year.
Dr Feng said it was possible they were affecting the rock lobster fishery - WA's most prized - and research was under way to determine what links existed.
Rock lobster fishermen have been watching with growing alarm the almost non-existent numbers of puerulus - baby crayfish - migrating back towards the coast so far this year.
This event, known as the "recruitment" of puerulus, is used by the department and fishermen as an important indicator of future lobster numbers.
After a bumper recruitment last year when average ocean conditions were recorded, Dr Feng said it seemed the reverse applied when temperatures were abnormal.
He said warm winters, in particular, were problematic because they caused larvae to be released "too early".
The comments come amid signs other fisheries are being affected by the unusual conditions.
Stocks of prawns, crabs and abalone off WA's Gascoyne and Mid West coast are still recovering from the marine heatwave in 2010-11, when temperatures soared up to 5C above normal.
The Environmental Protection Authority said this year's collapse of Cockburn Sound's crab fishery, the second time in eight years, was at least partly caused by high marine temperatures.
