By Dr Bruce Mann
The 49th Pondoland Marine Protected Area (MPA) fish monitoring field trip was undertaken from 17-18 July 2020. Having missed the April trip due to lockdown, the team led by ORI senior scientist, Dr Bruce Mann, were itching to get back out onto the water again! This project primarily uses controlled research fishing and tagging as part of ORI’s ongoing investigation into the effectiveness of this MPA.
CONTROLLED FISHING SURVEY
Overall, 115 fish (56%) were caught in the no-take area, which amounted to 12.8 fish caught per angler per hour. Fishing in the exploited area was also surprisingly good and 89 fish (44%) were caught amounting to 11.4 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 (near perfect) weather conditions. The team recorded 12 fish species in the no-take area and 13 species in the exploited area. Species composition was dominated by slinger, scotsman, Natal seacatfish and yellowbelly rockcod in the no-take area, while catches in the exploited area were dominated by halfmoon rockcod, scotsman, Natal emperor and Natal seacatfish. As usual, the average size of fish caught was generally much larger in the no-take area.
A total of 92 fish were tagged overall with 51 tagged in the no-take area and 41 in the exploited area. Over the two days the team recaptured a remarkable 22 fish with 15 coming from the no-take area and 7 recaptures from the exploited area. The fish with the greatest distance moved was a scotsman that moved 1175 m in the Mtentu sampling area. All other recaptures moved a lot less with the average distance being a mere 208 m from where they were originally tagged. This indicates the high level of residency of most reef fish. The fish with the longest time at liberty were two yellowbelly rockcod which had been free for 1894 days (5.2 years) and 1830 days (5.0 years) respectively, one of which had been recaptured 3 times. Interestingly, since the last field trip in January 2020, six recaptures have been reported caught by members of the angling public including two scotsmen, a catface rockcod, a yellowbelly rockcod, a black musselcracker and a slinger. All these fish (except one of the scotsmen) left the no-take area and travelled distances between 116 and 403 km northwards, providing good evidence of spillover.
During this field trip the team managed to tag their fifth big black musselcracker with an acoustic tag. It is the biggest cracker that they have tagged with an acoustic tag to date (900 mm FL). They also managed to tag another four flapnose houndsharks with acoustic tags bringing the total to six. It will certainly be interesting to see the movement behaviour of these animals in the future. Five acoustic receivers in the MPA were rolled over in June 2020 and the information downloaded off these receivers is nothing short of fascinating.
Since April 2006 (with a break between 2016-2017), the team have conducted extensive monitoring in the Pondoland MPA using multiple methods including research fishing, tag-recapture, underwater visual census, baited remote underwater video and monitoring movements of fish tagged with acoustic transmitters. From this research, it is very clear that the no-take area in the Pondoland MPA is providing an important refuge for many overexploited fish species. Many popular linefish species such as scotsman, slinger, yellowbelly rockcod, black musselcracker, etc. are much more abundant and of a much greater size in the no-take area than in the adjacent exploited area. Some species such as black musselcracker are known to spawn in this area and the increase in juvenile black musselcracker in the exploited area reported by local ski-boat anglers bears testimony to the potential of the no-take area to seed adjacent areas. Similarly, over time they have seen several adult fish species, especially scotsmen and slinger leaving the no-take area and moving northwards up the coast presumably to spawn in warmer waters. This provides further evidence of spillover from the MPA, which is helping to enhance fish populations in the exploited areas along our coast and providing direct benefit to fisheries.