Aaron Bartholomew

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.

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.

Faunal colonization of artificial seagrass plots: The importance of surface area versus space size relative to body size

An index of structural habitat complexity was devised: the average inter-structural space size within a habitat/the width of the prey organism of concern (Sp/Py). Prey survivorship should be low at Sp/Py<1 as the prey will be effectively excluded from using the habitat as refuge (they cannot maneuver through the spaces). At Sp/Py near to 1, survivorship should be high, as the spaces within the habitat are ideal for the prey and their predators are excluded (assuming they are larger than the prey). As Sp/Py increases, prey survivorship should drop rapidly until reaching a lower plateau where no predators are excluded by the structure. Sp/Py is dimensionless, and is potentially applicable across different scales and habitat types. Some of the predictions of this model were tested using artificial seagrass plots deployed in a seagrass bed in the York River, Virginia. The plots had 5 different structural treatments: control (a base with no ribbon), low, medium and high densities, as well as a heterogeneous treatment (composed of 1/3 low, medium and high density in a single treatment). The abundance of 2 mobile fauna size classes (<3.5 mm width and 3.5 to 9.5 mm width) and total species richness were compared among the different density treatments. The abundance of the smaller fauna increased with increasing density, and this response was proportional to the total surface area of the plots. The small fauna apparently did not respond to the smaller, ideal space sizes associated with the higher density plots. The larger fauna responded to the treatments as well, with the highest abundances occurring in the heterogeneous and high density treatments. The larger fauna did not respond to the structure proportional to the surface area within the plots, and its is possible that they responded to the inter-structural space sizes appropriate to their body sizes, although the results do not clearly support this conclusion. The different treatments did not affect species richness when the effect of total abundance on richness was controlled.

Rapidly entrainable tidal vertical migrations in the salt marsh snailLittoraria irrorata

The salt marsh periwinkleLittoraria irrorata (Say) remains on the substratum during low tide but climbs above the water on stalks ofSpartina alterniflora Loisel during high tide. Rhythmic tidal migrations may allowL. irrorata to avoid predators such as blue crabsCallinectes sapidus Rathbun that forage when the marsh is inundated. These tidal rhythms may be driven by endogenous clocks or they may be easily entrained. Snails with flexible and entrainable climbing rhythms may be able to avoid predators in unpredictable environments (e.g., when water unexpectedly covers the substratum as in storm surges). We tested the behavioral response ofL. irrorata to different simulated tidal regimes in the laboratory, and the effect of remaining above mean high water (MHW) on snail survivorship in a smallS. alterniflora salt marsh. In laboratory mesocosms, vertical snail position was measured under constant water levels, simulated tidal cycles, and simulated tidal cycles 180° out of phase (reversed). Under constant water levels, snails ceased to migrate vertically after 1 d. When exposed to tidal and reversed tidal cycles, snails migrated in synchrony with the appropriate simulated rhythm.L. irrorata entrained quickly to differing tidal cycles and maintained their position above the water surfce when water levels were high. In a field experiment, snails were tethered toS. alteriflora plants near the substratum and above MHW in the marsh for 1 wk to assess survival. Survival of snails tethered above MHW was sigificantly greater than for snails tethered at the base of plants; no snails in control cages died. Rapid alteration of tidal vertical migrations may allowL. irrorata to avoid predators that forage when water inundates the marsh predictably or unexpectedly.

Man-Made Structures as Artificial Reefs in the Gulf

Over 70% of the largest cities on earth are associated with seashores (Duarte et al. 2008), and two thirds of the human population lives within 100 km of a coast (UNEP 2002). The Gulf is no exception, with most major urban centers directly adjacent to coasts, with its people both culturally and economically tied to marine resources. Coastal development has rapidly expanded in the Gulf since the 1950s, leading to an increase in the exploitation of coastal marine resources and the degradation of coastal habitats (Al-Madani et al. 1991; Mohammed and Al-Sadh 1996). Coastal fisheries throughout the Gulf are being increasingly exploited, with demersal reef fisheries stocks declining by over four-fifths in the past three decades (see Chap. 8), while dredging, reclamation, and associated coastal development activities have contributed to the permanent loss or long-term degradation of important intertidal, sea-grass, mangrove, and coral reef habitats throughout the Gulf (Price 1993; Al-Jamali et al. 2005; Khan 2007; Burt et al. 2008, 2009b; Maghsoudlou et al. 2008; Sheppard et al. 2010, chapter 16). It is likely that such impacts will accelerate in the coming decades as population continues to grow and become progressively more urbanized along the Gulf’s coastlines (GRWv3 2005).

Space size relative to prey width and total cover in an area both influence the habitat choices of freshwater angelfish Pterophyllum scalare in mesocosms

Prey survivorship can vary with average space size/prey width (Sp/Py) and total cover within an area (Ct/At). Hypotheses predict that prey survivorship is maximized at intermediate Sp/Py values and that prey survivorship increases rapidly from zero to low cover but increases at a slower rate as cover increases further. Freshwater angelfish Pterophyllum scalare made choices between artificial vegetation treatments consistent with these predictions. At constant low cover, fish did not exhibit any space width preferences. At constant medium cover, fish significantly preferred a narrower space treatment over a wider space treatment. At constant high cover, fish significantly preferred a wider space treatment over narrower space treatments. At constant Sp/Py, fish exhibited a marked preference for a higher-cover treatment at low-cover levels. They also preferred higher cover treatments under higher cover levels, but these preferences were not as pronounced. Sp/Py and Ct/At both influenced the fishes’ habitat choices.

Both decreasing interstructural space size and increasing total cover increase shrimp abundance on artificial structures deployed in a UAE seagrass bed

We tested whether total cover and interstructural space size affect the abundances of mobile fauna colonizing small artificial structures deployed in a seagrass bed near Dubai, UAE, during May and September 2011. There were three complexity treatments: low cover with wide interstructural space sizes, high cover with wide space sizes, and high cover with narrow space sizes. This is the first study to deploy structures that vary interstructural space size while keeping cover constant and that vary cover while keeping interstructural space size constant. Shrimp had significantly higher abundance in the high cover/narrow space treatment compared with the low cover/wide space treatment. Complexity did not affect the abundances of most fauna. There were differences in the abundances of nudibranchs, amphipods, cumaceans, fish, shrimp, isopods, and crabs between the two deployment times. This is the first study demonstrating possible seasonal differences in UAE seagrass fauna.

Drivers and challenges for implementing ISO 14001 environmental management systems in an emerging Gulf Arab country

Worldwide, ISO 14001 certification for organizations has become the norm, but the Arab world accounts for an insignificant portion of all the certified organizations. There is a dearth of research on environmental management systems (EMS) in Arab and emerging countries and in public organizations. The objectives of this research are to: (1) examine the key drivers and challenges related to implementation of ISO 14001 certified EMS in the United Arab Emirates, an emerging Arab country and (2) compare and contrast these drivers and challenges between private and public organizations. We adopt an explorative, qualitative methodology, using semi-structured interviews with environmental managers in 11 organizations (6 private and 5 public) from different industrial sectors. Drivers of EMS certification were mostly similar between private and public organizations, with some differences. Compliance with regulations and standards, and increasing environmental performance were the main drivers for ISO 14001 certification in both private and public organizations. Commitment to sustainability was more important for public organizations. Cost reduction, competitors, leadership commitment and customers’ demands were shared drivers, but more stressed by private organizations. Local community and employees’ pressures were reported by private organizations only. The challenges to ISO 14001 implementation were similar for private and public organizations. They were: a lack of qualified human resources, practical challenges associated with implementation, a lack of regulations, a lack of support from management, and high costs. Our findings have implications for managers, academics, consultants, and policy makers in the UAE and other emerging markets.