70 years of helping people to care for our ocean

The 52nd Pondoland Marine Protected Area boat-based fish monitoring field trip

By Dr Bruce Mann 

The 52nd Pondoland Marine Protected Area (PMPA) fish monitoring field trip was undertaken from 12-13 October 2021. This project has been running since 2006 and primarily uses controlled research fishing and tagging as part of ORI’s ongoing investigation into the effectiveness of this MPA. ORI senior scientist, Dr Bruce Mann led the team of five anglers – four SAAMBR staff members and one guest angler. Sea conditions were calm with a ~1.5 m swell and a light north-easterly wind on both days gusting up to a maximum of 12 knots. The water was “Pondo green” (4-6 m viz) and cool (20°C) with a slight N-S current.

Fishing was conducted using standardised bottom traces with barbless circle hooks. All fish caught were carefully handled and released unharmed. Overall, 102 fish (56%) were caught in the no-take area, which amounted to 10.3 fish caught per angler per hour. Fishing in the exploited area was relatively good this trip with 81 fish (44%) caught amounting to 8.4 fish caught per angler per hour. This was after the same amount of fishing effort in both areas in two successive days of fishing with very similar weather conditions. The team recorded a total of 17 fish species, with 11 species caught in the no-take area and 13 species in the exploited area. Species composition was dominated by Natal seacatfish (36), scotsman (19), slinger (17) and yellowbelly rockcod (9) in the no-take area, while catches in the exploited area were dominated by scotsman (18), black musselcracker (14), Natal emperor (13) and Natal seacatfish (10).

A total of 84 fish were tagged overall with 41 tagged in the no-take area and a remarkable 43 in the exploited area. This is the first time in 14 years that we have tagged more fish in the exploited area. Scotsman was the most common species tagged (n=24), followed by black musselcracker (n=18) and catface rockcod (n=9). Over the two days we recaptured a remarkable 16 fish with 9 coming from the no-take area and 7 recaptures from the exploited area. The 16 recaptures included 8 scotsmen, 3 yellowbelly rockcod, 2 black musselcracker, 1 halfmoon rockcod, 1 Natal emperor and 1 flapnosed houndshark. The fish with the greatest distance moved was a scotsman that moved 389 m in the Mkambati sampling area. All other recaptures moved smaller distances, with the average distance being a mere 159 m from where they were originally tagged. This indicates the high level of residency of most reef fish and their relatively small home range sizes. The fish with the longest time at liberty was the halfmoon rockcod that had been free for 5.6 years. We also recaptured a scotsman and a flapnosed houndshark that had both been free for 3 years. The movement and growth rate information obtained from these recaptures is extremely valuable.

Since the last field trip in January 2021, we have had no less than 15 recaptures reported to us by members of the angling public. This information is quite incredible and undoubtedly shows a degree of spillover taking place from the PMPA. The fish that moved the greatest distance were two slinger both tagged off Mkambati and recaptured by commercial ski-boat fishermen off Dawson’s Rock north of Richards Bay. The fish with the longest time at liberty was a scotsman originally tagged off Mkambati and recaptured for a third time six years later off Mzamba. Unfortunately, the angler that recaptured one of the black musselcrackers (it was one of our large acoustically tagged fish) was unwilling to provide any information on the recapture.

 

 

 

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