Lobster trap impact on coral reefs: Effects of wind‐driven trap movement

Commercial fishers report finding their lobster traps often great distances from their original location following major hurricanes. But traps also move during lesser wind events, such as during winter cold fronts. To assess trap impact on coral communities following winter storms, lobster traps were placed in hardbottom and reef habitats commonly used by commercial fishers in the Florida Keys, United States. Trap movement, percentage benthic faunal cover, and benthic faunal damage were assessed after 26 wind events occuring over three winters. Traps moved when storms with sustained winds greater than 15 knots (27.8 km/h) persisted for more than 2 days. Winter storms above this threshold moved buoyed traps a mean (±SE) distance of 3.63 ± 0.62 m, 3.21 ± 0.36 m, and 0.73 ± 0.15 m per trap and affected a mean area of 4.66 ± 0.76 m², 2.88 ± 0.29 m², and 1.06 ± 0.17 m², per trap at 4‐m, 8‐m, and 12‐m depths, respectively. Unbuoyed traps, simulating derelict traps, moved a mean distance of 0.43 ± 0.08 m and 0.44 ± 0.02 m, and affected a mean area of 0.77 ± 0.06 m² and 0.90 ± 0.08 m² per trap at 4‐m and 8‐m depths, respectively. Injuries caused by trap movement included scraped, fragmented, and dislodged sessile fauna, resulting in significant damage to stony coral, octocoral, and sponges. Overall, sessile fauna cover along the trap movement path was reduced from 45% to 31%, 51% to 41%, and 41% to 35% at the 4‐m, 8‐m, and 12‐m sites, respectively. Because of the large numbers of traps deployed and reported lost each season, damage to sessile fauna and loss of benthic faunal cover caused by traps needs to be considered to effectively protect coral reefs and manage essential fishery habitat in the future.     

Movement patterns of individual migrating western rock lobster,Panulirus cygnus,in Western Australia

Abstract

Migrating and pre‐migrating western rock lobster Panulirus cygnus were tagged with datastorage tags that recorded temperature and pressure, which was converted to depth (Pressure (kPa) — surface pressure (kPa)/10)) at Dongara and Jurien Bay in Western Australia between December 2005 and December 2007. All lobsters were fitted with tag flotation devices, and returns were made by either commercial fishers or beachcombers who located detached tags. A total of 135 lobsters were released with “backpack” flotation tags, but only 84 (62.2%) of the backpacks carried data‐storage tags. Depths of release ranged from 5 to 113 m. Of the tagged lobsters released, commercial fishers recaptured 52 (38.5%), whereas 11 tags (8.1%) were found by beachcombers. At least 33%, and possibly up to 63%, of animals identified by their pale coloration as pre‐migrating individuals, failed to migrate. Those that did migrate (n = 11) were at liberty from 1 to 94 days and showed generally similar movement patterns in that they migrated only at night from darkness (after 2000 h) until after moonrise. However, their movement patterns were less constrained by the rising of the moon in deep water. Only 27% migrated nightly, compared with 73% that skipped migrating on one or more nights, to restart some days later. This latter proportion would likely have been considerably greater, but some migrating animals were only at large for short periods before recapture, and therefore had little time to show any variation to the nocturnal migration pattern. Individual speeds of migration during periods of activity were estimated for nine lobsters as 0.20 to 0.68 km h^?1, with a mean speed of 0.44 km h^?1, or 7.4 m min^?1. Improved knowledge of daily movement patterns resulting from this study provides a potentially important input into technological improvements in bait and pot design.     

THE SPINY-LOBSTER FISHERY IN CUBA*

ABSTRACT. The spiny-lobster fishery, the most valuable fishery in Cuba, is unique among those in major lobster-producing countries because of its combination of strong central control and absence of standardization and mechanization in fishing gear. Cooperation rather than competition among fishing vessels is promoted by exclusive fishing zones and fleet organization. These measures, along with the use of storage centers, simple vessels, and inexpensively constructed fishing gear, have promoted spatial rationality and cost reduction in the fishery and made it one of the most successful spiny-lobster fisheries in the world.     

徐家河水库枝角类优势种群与近太湖新银鱼关系的初步研究

于 1 995年 6月— 1 997年 1 2月 ,对徐家河水库枝角类优势种群的密度和近太湖新银鱼 (Neosalanxpseudotaihuensis)的生物量 (单位努力量渔获量 )进行了初步调查 ,以期研究银鱼与浮游动物的关系。结果表明 ,在 1 995年银鱼的生物量较高时 ,透明薄皮 (Leptodorakindti)、盔形 (Daphniagaleata)和模糊秀体 (Diaphanosomadubia)等大型枝角类的密度较低 ;在 1 997年银鱼的生物量较低时 ,这三种枝角类的密度则较高。而象鼻 (Bosminaspp )这样的小型枝角类恰恰相反 ,当银鱼的生物量较高时 ,其密度较高 ;反之 ,其密度较低。表明银鱼可以对枝角类产生显著的影响     

Factors that influence the entry–exit decision and intensity of participation of fishing fleet for the Galapagos lobster fishery

The Galapagos Islands are a prime example of a place where fishery management policies have been established without first understanding the behavior of fishermen. Since the creation of the Galapagos Marine Reserve in 1998, there has not been a single study in the archipelago that investigates fishing behavior and the factors affecting this behavior. This paper addresses this gap in the literature by describing and analyzing the decisions of the fishing fleet for the red spiny lobster fishery. It focuses on factors that affect the short-term decisions regarding both participation and intensity of participation in the lobster fishery. This paper finds that the fishing fleet in the Galapagos Islands behaves as profit maximizing firms, because they consider all the benefits and costs that affect both their participation decision as well as their decision about how frequently to be active after they have decided to participate. The results also show that there is a large latent effort in the lobster fisheries that could threaten the sustainability of any initiatives aimed at increasing catchability, prices, or markets. It is expected that this analysis will be valuable to policy makers when designing or improving the management plans for Galapagos fisheries.     

Long‐term trends in the recreational lobster fishery of Florida,United States: Landings,effort, and implications for management

In Florida, United States, the Caribbean spiny lobster, Panulirus argus, supports an important commercial fishery and also perhaps the most intensive recreational fishery of any lobster species, with sales of recreational lobster fishing permits exceeding 100 000 annually. For the past decade, we have used mail surveys of recreational lobster license holders to estimate spatially explicit landings and fishing effort when recreational fishers are most active—during the state's “Special Two‐Day Sport Season”, which takes place just before the opening of the commercial season, and during the first month of the regular recreational season, which coincides with the commercial season. From 1993 through 2002, fishing effort during the Special Two‐Day Sport Season has ranged from 60 000 to 112 000 person‐days, and landings have ranged from c. 112 to 255t. Both fishing effort and landings have varied without trend. Fishing effort during the regular season over the same period has ranged from 261 000 to 514 000 person‐days, and landings have ranged from 434 to 825 t. Fishing effort has shown a marginally statistically significant decreasing trend, the result of a progressive decrease in effort since 1999. The largest proportion of both fishing effort and landings was concentrated along the south‐east coast. Despite the recent decrease in landings, the proportion of total landings made by the recreational fishery has increased. From 1993 through 1998, the fishery was responsible for c. 30% of commercial landings; by 2001, that percentage increased to nearly 40%. Such a shift in landings away from the commercial trap fishery toward the recreational fishery was recognised as a potential but unintended effect of the ongoing management plan of restricting effort in the commercial trap fishery. Our 2001 surveys revealed that recreational lobster fishers spent more on a person‐day basis than the general visitor to the Florida Keys did, but less than those visitors using the region's coral reefs. Consequently, managers must establish management strategies that allow the coexistence of this resource's user groups and also incorporate the social and environmental concerns of nonuser groups.     

Puerulus and juvenile abundance in the rock lobster Jasus edwardsii at Stewart Island,New Zealand (Note)

Settlement of puerulus‐stage New Zealand red rock lobsters (Jasus edwardsii) and abundance of the first three juvenile cohorts were measured from 1981 to 1989 near Halfmoon Bay, Stewart Island. Puerulus settlement on subtidal collectors shows great annual variation. Juvenile abundance, estimated from the number caught in annual diver collections, shows less variation. One‐year‐olds appear less vulnerable to diver sampling than older juveniles. Abundance of 2‐ and 3‐year‐olds is highly correlated with puerulus settlement 2 and 3 years previously. Survival between puerulus and 1+ stages appears to be density‐dependent, but survival of older juveniles does not. Size is inversely related to abundance in 3+ females but not in the other cohorts, suggesting density‐dependent growth between ages 2 and 3. Puerulus settlement rates and processes on shallow inshore reefs appear to be important in determining recruitment strength in this species.