Summary

The regulation of recreational hook-and-line fisheries in NSW mostly involves legal lengths and daily bag limits.  It is assumed that the majority of released fish survive.  However, a lack of information on the fate of most species makes it difficult to estimate the benefits of current management.  The following study provides a first step in addressing this issue for mulloway.

The work aimed to determine the short-term survival of mulloway after being released with either (i) the hook removed as per normal fishing practices or (ii) the line cut and the hook left in the fish.  Approximately 250 mulloway (between 25 and 45 cm total length) were distributed among seven 5000 l fibreglass tanks positioned around a large flow-through pool containing six cylindrical sea cages.  Ninety one mulloway were hooked from five of the 5000 tanks using the same type and size of J-hooks baited with school prawns, and then released into four of the sea cages.  During capture, most fish were observed to either swallow the hook or were hooked in the gill arch or upper mouth or jaw.  Immediately after being caught, 45 of the hooked fish were randomly selected and had their hooks removed prior to being released into two designated sea cages.  The remaining 46 fish had the line cut and their hooks left in before being placed into two separate sea cages.  Once all hooked fish were released, 46 control fish were transferred (using scoop nets) from two of the 5000 l tanks to the remaining two sea cages.  Fish in all sea cages were monitored and fed prawns for 5 days.

All of the mulloway in the control group survived.  In comparison, 24 of the hooked and released fish died, providing a total survival rate of 73.6%.  Mortalities remained similar between those fish that had the hook removed (14 deaths) or left in (10 deaths), with survival rates of 68.8 and 78.2%, respectively.  Irrespective of the treatment, most fish that died did so during the first and second days after release.

While the results suggest that a large percentage of mulloway survive the process of being hooked and released, additional research is required to more closely examine the factors that might influence survival, including the effects of hook location (i.e. swallowing the hook vs. being hooked in the mouth), hook and rig type, depth of capture and handling and exposure to air following landing.  NSW DPI will be examining some of these issues, as well as changes to handling procedures that might minimise mortalities.  This information will contribute towards improving the survival of mulloway released by recreational anglers.