Tagged poenskop recaptured 18 years after release

  • 14 July 2014 | Stuart Dunlop and Jade Maggs, ORI

Since 1984, the Oceanographic Research Institute (ORI), with the help of conservation-conscious anglers, has been tagging important linefish species off the coast of Southern Africa.

To date the project has captured, tagged and released 270 000 fish, of which approximately 14 000 have already been recaptured.

Most recaptures take place close to where the fish is released and relatively soon afterwards. On the odd occasion, tagged fish have moved considerable distances over a short space of time, while others have survived at liberty for lengthy periods, not moving very far. However, every now and then the linefish research team at ORI is blown away by a remarkable recapture.

Poenskop (Cymatoceps nasutus) recaptured 18 years after release

On 28 May 2014, Amanda Liebenberg reported to us that her father, Dirk Liebenberg, a commercial fisherman from Port Edward on the KwaZulu-Natal South Coast, had captured a tagged poenskop (Cymatoceps nasutus), or black musselcracker, off Glenmore, slightly north of Port Edward.

In the nearby Pondoland Marine Protected Area (MPA), ORI scientists have been tagging fish on a quarterly basis for the past eight years. Dirk regularly recaptures ORI-tagged fish, which have moved out the MPA and diligently reports these to us. However, on 28 May, Dirk had no way of knowing that the tagged poenskop, which he had just caught, had been tagged 18 years earlier, on 6 October 1995, by recreational ski-boat angler Jordan Lentz.

Not only had this fish survived for an incredible length of time but it had moved some 314km up the coast from a reef off the Cintsa River in the Border region, where it was originally tagged.

During the 18 years at liberty, the poenskop had only grown 255mm to measure 845mm from the tip of the nose to the fork in the tail. It weighed 19.5 kg. At this size, the fish would most likely have been a mature male with an estimated age of about 28 years (this species changes sex from female to male at about 18 years of age). It had most probably moved up the coast with the intention of spawning in warmer waters.

Recaptures such as this confirm the ageing work done on this species using sectioned otoliths (ear bones). Poenskop have been aged at a remarkable 45 years. The recapture also provides evidence to suggest that although juvenile poenskop are more likely to be resident, adults gradually move up the coast in a north-easterly direction.

Through the tagging project, similar behaviour has been recorded in other important reef fish species such as red steenbras and seventy-four. Marine Protected Areas like the one in Pondoland are critical refuges for these large adults, which have migrated up from the cooler waters of the Cape to spawn.

Protection of spawning stock in Marine Protected Areas allows these large adults to spawn and continuously supply adjacent reefs with young fish.

Thank you to all the anglers who tag fish on behalf of ORI and to those who report recaptures. Your support is invaluable to marine conservation.

If you catch a tagged fish, you can contribute greatly to our understanding and the conservation of our linefish species by reporting the tag number to ORI via our online facility at oritag@ori.org.za or by calling +27 (0)79 529 0711. Do your bit to help protect our invaluable fish stocks.

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