James A. Bohnsack

A Review of Catch-and-Release Angling Mortality with Implications for No-take Reserves

Management agencies have increasingly relied on size limits, daily bag or trip limits, quotas, and seasonal closures to manage fishing in recreational and commercial fisheries. Another trend is to establish aquatic protected areas, including no-take reserves (NTRs), to promote sustainable fisheries and protect aquatic ecosystems. Some anglers, assuming that no serious harm befalls the fish, advocate allowing catch-and-release (C&R) angling in aquatic protected areas. The ultimate success of these regulations and C&R angling depends on ensuring high release survival rates by minimizing injury and mortality. To evaluate the potential effectiveness of these practices, we review trends in C&R fishing and factors that influence release mortality. Analysis of Marine Recreational Fishery Statistic Survey (MRFSS) data for 1981–1999 showed no statistically significant U.S. trends for total number of anglers (mean 7.7 × 106), total catch in numbers (mean 362 × 106), or total annual catch/angler (mean 42.6 fish). However, mean total annual landings declined 28% (188.5 to 135.7 × 106), mean total catch/angler/trip declined 22.1% (0.95 to 0.74 fish), and mean landings/angler/trip declined 27% (0.42 to 0.31 fish). The total number of recreational releases or discards increased 97.1% (98.0 to 193.2 × 106) and as a proportion of total catch from 34.2% in 1981 to 58.0% in 1999. Evidence indicates that the increased releases and discards are primarily in response to mandatory regulations and to a lesser extent, voluntary releases. Total annual catch and mean annual catch/angler were maintained despite declines in catch per trip because anglers took 30.8% more fishing trips (43.5 to 56.9 × 106), perhaps to compensate for greater use of bag and size limits. We reviewed 53 release mortality studies, doubling the number of estimates since Muoneke and Childress (1994) reviewed catch and release fishing. A meta-analysis of combined data (n=274) showed a skewed distribution of release mortality (median 11%, mean 18%, range 0–95%). Mortality distributions were similar for salmonids, marine, and freshwater species. Mean mortality varied greatly by species and within species, anatomical hooking location was the most important mortality factor. Other significant mortality factors were: use of natural bait, removing hooks from deeply hooked fish, use of J-hooks (vs. circle hooks), deeper depth of capture, warm water temperatures, and extended playing and handling times. Barbed hooks had marginally higher mortality than barbless hooks. Based on numbers of estimates, no statistically significant overall effects were found for fish size, hook size, venting to deflate fish caught at depth, or use of treble vs. single hooks. Catch and release fishing is a growing and an increasingly important activity. The common occurrence of release mortality, however, requires careful evaluation for achieving fishery management goals and in some cases, disturbance, injury, or mortality may conflict with some goals of NTRs. Research is needed to develop better technology and techniques to reduce release mortality, to assess mortality from predation during capture and after release, to determine cumulative mortality from multiple hooking and release events, and to measure sub-lethal effects on behavior, physical condition, growth, and reproduction.

Effectiveness of an existing estuarine no-take fish sanctuary within the Kennedy Space Center, Florida

Abstract Approximately 22% of the waters of the Merritt Island National Wildlife Refuge, which encompasses the Kennedy Space Center, Florida, have been closed to public access and fishing since 1962. These closed areas offer an opportunity to test the effectiveness of “no-take” sanctuaries by analyzing two replicated estuarine areas. Areas open and closed to fishing were sampled from Nov 1986 to Jan 1990 with 653 random trammel-net sets, each enclosing 3,721 m2. Samples from no-fishing areas had significantly (P < 0.05) greater abundance and larger fishes than fished areas. Relative abundance (standardized catch per unit effort, CPUE) in protected areas (6.4 fish/set) was 2.6 times greater than in the fished areas (2.4 fish/set) for total game fish, 2.4 times greater for spotted seatrout Cynoscion nebulosus, 6.3 times greater for red drum Sciaenops ocellatus, 12.8 times greater for black drum Pogonias cromis, 5.3 times greater for common snook Centropomus undecimalis, and 2.6 times greater for striped mul...

An analysis of the loss of acroporid corals at Looe Key, Florida, USA: 1983-2000

Abstract. The Caribbean reef-building corals Acropora palmata and Acropora cervicornis have undergone widespread declines in the past two decades, leading to their designation as candidates for listing under the United States Endangered Species Act. Whole-reef censuses in 1983 and 2000 at Looe Key National Marine Sanctuary in the Florida Keys provide estimates of areal loss of live Acropora spp. cover. Area (square meters) of live coral cover was quantified from depiction on scaled base maps of extent of coral cover observed by a snorkeler on each reef spur at each census. Certain thickets appear to have been persistent (though none expanded), but the total area of live A. palmata at Looe Key is estimated to have declined by 93% and A. cervicornis by 98% during this 17-year interval. It is likely that acroporid populations may have already undergone substantial decline prior to our initial census in 1983.

Influence of marine reserve size and boundary length on the initial response of exploited reef fishes in the Florida Keys National Marine Sanctuary, USA

We examine the influence of reserve size and boundary length on the relative rate of fish density change in reserves versus fished reference reefs for three exploitable-sized reef fish categories: (1) combined fish (34 species of Haemulidae, Lutjanidae, Serranidae, and hogfish Lachnolaimus maximus); (2) Haemulidae (13 species); and (3) Lutjanidae (9 species). If reef habitat boundaries are highly permeable to fish movements then fish recovery within a reserve would be inversely proportional to: reserve perimeter (RP)/total reserve area (RA) (RP/RA). If, however, reef habitat boundaries are relatively impermeable barriers to fish movements, recovery within the reserve would be inversely proportional to: reserve boundary that intersects reef habitat (HI)/reef habitat area within the reserve (HA) (HI/HA). From 1994 to 2001 we monitored reef fishes within and outside of no-take marine reserves established in 1997 in the Florida Keys, USA. A significant majority of reserves had greater rates of density change than reference reefs for Lutjanidae and combined fish (22 of 24 reserves for both categories). Significantly higher rates of density change were found in ten reserves for Lutjanidae, two reserves for combined fish, and one reserve for Haemulidae. Reserves appeared to promote an increased density of exploitable fishes. A significant, negative, but weakly correlated relationship was found between the relative rate of density change (RDC) for combined fish and the HI/HA ratio. Reserve size and placement appeared to have a minimal effect upon RDC.

An Extensive Deep Reef Terrace on the Tortugas Bank, Florida Keys National Marine Sanctuary

While most of the mapped area (137.5 km 2 ) of the Tortugas Bank consists of low-relief hard-bottom (105.5 km 2 or 77%) and scattered, rocky outcrops (16.6 km 2 or 12%), a sizeable portion of the western rim or platform edge (24 o 42.30’ N, 83 o 02.64’ W) is a well-developed reef terrace community (top panel). The topography of the substratum is very complex, owing to the numerous undercuts and caverns, as well as mushroom-shaped and plating corals up to 2 m in height. Coral cover is high (26.3 to 28.3% among three sites visited) relative to offshore reefs in the Florida Keys and is dominated by Montastraea faveolata, M. franksi, M. cavernosa, and Siderastrea siderea. The terrace community is a deeper version (22-27 m) of the reef terraces near Loggerhead Key 15 km to the southeast in Dry Tortugas National Park (Davis 1982). Anecdotal observations suggested that the western edge of the Tortugas Bank, locally named Sherwood Forest because of the predominance of mushroom-shaped corals (bottom panel), was spatially extensive. Using a combination of side-scan sonar, diver surveys, and bathymetry data, we estimate that the reef terrace is approximately 15 km 2 or about 10% of the mapped area of the Tortugas Bank. The “discovery” of this area by our science team was clearly preceded by the knowledgeable and active fishers of the region. Despite the remoteness of the Dry Tortugas relative to the Florida Keys, and the well developed reef structure, preliminary data indicate evidence of overfishing by a general absence of large species and individuals among exploited species, especially grouper (Serranidae) and snapper (Lutjanidae). Also, surprisingly few shark and barracuda were observed, and there was evidence of shrimp trawl damage to hard-bottom habitat. Because remoteness does not guarantee protection, the implementation of marine reserves in this region holds promise for restoration of fish stocks and protection of one of the largest areas of well-developed and previously undescribed coral reefs in Florida.