De Hoop MPA Monitoring Program

Our Website

Science communication is challenging. Scientific jargon, restricted access journals and a tendency for scientists to get ‘lost in the detail’ inhibit the flow of information to those genuinely interested. Here, we aim to provide the general public an overview of the data collected by the De Hoop monitoring programme on a platform that is easy to use, understandable and accessible to all to browse in their own time. The website contains the results of 30 years of fishery-independent monitoring of surf-zone fish abundance in the De Hoop Marine Protected Area. It is not exhaustive, but rather illustrates the basic provisions of fish monitoring programmes: total catch, catch-per-unit-effort and size-structure data. These can be used as indicators of fish abundance and a benchmark for assessments in exploited areas. Moreover, the data are used to measure natural variation in these parameters over time and between sites. Natural trends in abundance and the scale of such variation are important for assessing the impact of fishing and for determining catch regulation.

The De Hoop Marine Protected Area

South Africa has a very rich fish fauna. We have over 2200 species of marine fish – and 600 of these are directly affected by fishing. Our iconic angling species are endemic to southern Africa – including our national fish, the galjoen, the massive dusky kob and the powerful white steenbras. Unfortunately, these are now at a small fraction of their original abundances, following relentless exploitation across the length of the South African coastline. Marine Protected Areas (MPAs) are globally recognised as a necessary strategy to protect and recover fish populations and the World Parks Congress called for 20% of the worlds ocean to be protected from fishing.

De Hoop is one of several MPAs around the South African coast where fishing is prohibited. In fact, De Hoop is one of the largest stretches of protected coast in the country. The fish populations here have been undisturbed since 1985. One of the objectives of the De Hoop Marine Protected Area is to aid in the protection and recovery of species that have been severely impacted by fishing. To monitor the status of fish populations and the efficacy of the MPA, the Department of Environmental Affairs runs a research project at De Hoop, involving scientists from the University of Cape Town and volunteer anglers.

Monitoring Coastal Fishes

South Africa’s surf-zone fish community is generally distinct from the offshore reef, soft-bottom and pelagic fish assemblages. Although some species might be caught from the shore and from boats, the majority of surf-fishes are limited to the narrow coastal zone and intertidal waters. For example elf is the most dominant shore-based catch, but it is a minor contributor to the boat-based catch. In contrast, reef fish, such as roman Chrysoblephus laticeps, is a target of boat fishermen and are only infrequently taken by shore anglers who can access deep water. Surf-zone fishes frequent the high-energy, wave exposed sandy beaches and shores of mixed rock and sand, and include many species seldom found outside the cover of broken surf. The surf-zone fish assemblage is therefore treated separately from other assemblages, and it requires dedicated monitoring.

Consensus on how to monitor surf-zone fish or the fishery in a cost effective manner has yet been achieved. The many attempts at monitoring to date have been disjointed and seldom sustained, being reliant of donor research funding or studentships. Monitoring takes on two forms, fishery-dependent and fishery-independent. The former involves creel surveys (e.g. Hutchings et al 2009). The latter relies on monitoring of fish directly by researchers, who may use the same fishing methods as those employed in the fishery, which has the advantage of providing comparable statistics, or it may involve other non-lethal methods, which have the advantage of providing supplementary information, such as post-release movement patterns.

The wave-exposed shoreline presents a number of difficulties for fishery-independent surveys. This habitat is not suitable for underwater observation whether by SCUBA or camera, because of the turbulence of the water. The use of seine-nets (e.g. Clarke et al 1996) is suitable only on pure-sandy beaches, and cannot be used to monitor the rich reef-associated assemblage. Suspended gill-nets have nets have been used in sheltered bays, but have the disadvantage of being lethal to fish. Fish recruitment has been surveyed using poisons and specialised nets, but again these methods are restricted to sheltered waters and are, in addition, labours intensive.

Surveys of surf-zone fish populations are probably best done by angling. This method has the advantages that it (1) covers all the species affected by the fishery, (2) provides data comparable to the recreational fishery, (3) can be applied without killing fish and (4) allows the capture of fish for non-lethal sampling (e.g. genetic sampling), lethal sampling (e.g. age determination) and tagging for movement or population estimation (e.g. Attwood and Cowley 2005). This type of monitoring is now undertaken in four MPAs, with the aim of providing information on the natural state and variation of fish populations and communities.

The De Hoop MPA Monitoring Programme

The De Hoop monitoring programme occurs at two sites within the MPA: Koppie Alleen and Lekkerwater. Each year, six trips are undertaken with each site being sampled three times. Anglers catch, tag and release fish, recording vital information on their abundance, size and movement habits. The project began in 1984, one year before the Marine Protected Area was established, and has continued ever since, making it the longest project of its kind. The results have been cited worldwide in support of marine protected areas and fish conservation.

Fish taggers use standard angling techniques, but take great care when handling each fish before returning them to the water. Each fish is identified and measured, and some of them are tagged with a plastic dart tag bearing a unique number and a return address. When anglers catch these fish outside of De Hoop, they are expected to report the data. On any given day, anglers are nominated to target small fish (galjoen), big fish (dusky kob, white steenbras etc.) or sharks (bronze whalers etc.). Anglers are required to note where fish are caught, how long they spent fishing and if they have lost any fishing tackle.

A surprisingly large number of the tagged fish have been recaptured – each one of these has yielded important information allowing scientists to estimate the degree site fidelity, their longevity and the rate of growth. The recapture statistics have been used to estimate the number of fish in the surf zone.

Data Selection

Data Selection

Data Selection

Data Selection