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The Caribbean spiny lobster , Panulirus argus , fisheries
| Content Provider | Semantic Scholar |
|---|---|
| Author | Ehrhardt, Nelson M. Puga, Rafael Butler, Mark J. |
| Copyright Year | 2009 |
| Abstract | The Caribbean spiny lobster is one of the most economically important resources to Caribbean fisheries. High demand and low supply of spiny lobster has driven most fisheries to an excess of fishing capacity and created overfishing conditions in most fisheries. All fisheries are recruitment driven and in the last 10 years recruitment has followed decreasing trends in most fisheries. Along with exploitation, changes in environmental and ecological conditions are likely to be impacting spiny lobster habitat. Population dynamics and fisheries processes that are key to the ecosystem approach to fishery management of the resources are identified and discussed. Introduction The Caribbean spiny lobster, Panulirus argus, sustains one of the most economically important fisheries in the region with the greatest stock abundances observed in the Western Caribbean and Brazil (Fig. 1). Fisheries developed from circumstantial operations in the early 1960’s to fully overcapitalized industries in the 2000’s. Landings peaked during 19871997 at about 32 to 37 thousand metric tons whole weight with a value exceeding US$300 million dock side. Regional landings decreased 55% in the 2000’s (Fig. 2) mostly due to intensive exploitation but also due to environmental and ecological changes in the spiny lobster habitat. High demand and reduced supply significantly increased prices paid for lobster and have promoted further overcapitalization. Industries and governments are concerned about the existing conditions that may generate missed management opportunities. Management of the resource is unilaterally attempted in most countries with regulations on minimum size, spawning season closures, and no-take of ripe (berried) females. Control of fishing capacities and landings are rare, and an overriding region-wide lack of enforcement and illegal fishing prevent an orderly utilization of the resource. In this work we briefly describe the main issues concerning the sustainability of Caribbean spiny lobster stocks, including their general biological characteristics that frame fisheries management and the core issues of fishery exploitation. Figure 1. Geographical distribution of the main commercial spiny lobster fisheries in the Western Central Atlantic Ocean. Figure 2. Total Caribbean wide (including Brazil) landings of Caribbean spiny lobster. Population dynamic considerations A significant issue regarding implementation of spiny lobster fishery management policies is the difficulty of defining units of stock due to the protracted planktonic lifespan of the larvae, which disperse in the open ocean before settling in a suitable juvenile habitat. Estimates of pelagic larval duration (PLD) for P. argus, extrapolated from modal progressions of phyllosomal stages from plankton samples, range from 6 12 months (Lewis, 1951; Sims and Ingle, 1966; Farmer et al., 1989). Only recently has this species been reared in captivity from egg through all its larval stages to the benthic juvenile stage with an observed PLD of 140 198 days (mean = 174 days; Matsuda et al. 2007). Given the strong ocean currents dominating the general environment where these larvae are found, it is plausible that they may colonize regions downstream -thus the Pan-Caribbean theory of spiny lobster population structure (Lyons 1980). This theory is supported by genetic studies showing a lack of geographical differentiation in P. argus stocks among Caribbean nations (Silberman, et al. 1994.a), an absence of seasonal variation in the genetic structure of postlarvae arriving at presumed “down stream areas” like the Florida Keys (Silberman, et al. 1994.b), and occasional intrusions of genetically distinct Brazilian P. argus postlarvae into Florida (Sarver, et al. 1999). Biophysical modeling of P. argus larval dispersal suggest that regional hydrodynamics can have a large impact on the degree to which local populations are self-recruiting or serve as sources of larvae for other regions (Lipcius et al 1997; Stockhausen and Lipcius 2001). A recent set of simulations of P. argus dispersal from 13 spawning sites in the Caribbean (Butler et al. 2008a) predicts that the majority of larvae released in the Caribbean may only disperse about 200km because of the strong effects of larval vertical migration on dispersal. However, other larvae in those simulations were advected thousands of kilometers from their natal source, the difference being that dispersal is also strongly affected by local oceanographic conditions. Although some P. argus fisheries located in strongly retentitive oceanographic environments probably experience significant selfrecruitment, there is likely a high degree of larval connectivity in the Caribbean. As more detailed and reliable estimates of larval dispersal come available, management of P. argus stocks should take into account the degree of self-recruitment likely for particular management units, but clearly management actions in one country may have consequences on other regional fisheries. Similarly, significant ecological shifts in some local spiny lobster habitats may be reflected on fisheries in other regions. The Caribbean spiny lobster larvae are dispersed in the prevailing ocean currents but can be retained in offshore gyres that are persistent enough to constrain their long-lived larvae (Fig. 3). The later are conspicuous in the Gulf of Honduras off Costa Rica-Panama, off South of Cuba and North of the Bahamas. Gyres and counter currents represent important physical mechanisms for local larval retention and combined with larval behavior (e.g., diel and ontogenetic vertical migration can significantly influene recruitment to local stocks (reviewed in Pineda et al. 2007), contributing to some of the most productive fisheries in the Caribbean (Fig. 3). Figure 3. Ocean currents expressed from satellite oceanographic buoys, areas of major larval retention, and main fisheries in the Caribbean region. Landings mostly correspond to fluctuations in recruitment because they consist primarily of new recruits (Fig. 4) (Cruz et al. 1995; Ehrhardt 2005a and 2007; Puga et al. 2008). Therefore, the dynamics of recruitment mechanisms and the resulting recruitment abundance play an overriding role on the outcome of local spiny lobster fisheries. Recruitment dynamic studies in Cuba (Cruz et al. 2001; Puga and de León 2003; Puga, et al. 2005, 2006, 2008), Florida (Ehrhardt and Fitchett, Submitted) and Nicaragua-Honduras (Ehrhardt 2005a) demonstrate the varying levels of complexity of the processes that control annual production. Figure 4. Recruitment driven landings in main Caribbean fisheries. However, along with postlarval supply sufficient nursery habitat is crucial for successful postlarval settlement and the growth and survival of juveniles that recruit to fisheries (reviewed in Butler et al. 2006). Those regions with the greatest P. argus fishery production in the Caribbean are those with the large shallow coastal zones with habitat suitable for nurturing juvenile lobsters. Indeed, local recruitment is not necessarily greatest in areas with the highest concentrations of arriving postlarvae (Herrnkind and Butler 1994; Lipcius et al. 1997), indeed the potential for habitat limitation of P. argus recruitment has been experimentally demonstrated in the Bahamas (Lipcius et al. 1997), Florida (Butler and Herrnkind 1992, 1997), and Mexico (Eggleston et al. 1990; Sosa-Cordero et al. 1998; Briones-Fourzan et al. 2001). This is compelling evidence of the importance of nursery habitat for fishery production. The protection of shallow-water nursery habitats for Caribbean spiny lobster should be of major importance to managers seeking to sustain viable fisheries. Settling P. argus postlarvae are attracted to the chemical and physical cues produced by red macroalgae and appear to also use pressure cues to select shallow water nursery habitats (Herrnkind and Butler 1986; Butler and Herrnkind 1991; Butler et al. 1997; Goldstein and Butler in review). Macroalgal rich hard-bottom and, secondarily, seagrass are the species preferred settlement habitats but areas with ample crevice shelters are crucial for high survival of later stage benthic juveniles (Marx and Herrnkind 1985; Herrnkind and Butler 1986; Eggleston et al. 1990; Acosta and Butler 1997; Herrnkind et al. 1997; Behringer et al. in press, Bertelsen et al. in press). Ecological studies carried out on spiny lobster habitat in Cuba recognize several fundamental environmental conditions as negatively impacting juvenile recruitment habitat including: 1) decreased amounts of natural and anthropogenic induced nutrients with the advent of dam constructions interrupting the natural runoff of nutrient rich fresh water to the spiny lobster habitat (Fig. 5; Puga et al. 2008), 2) increased salinity in juvenile habitats affecting larvae and prey species, 3) incidence of major and more frequent hurricanes impacting habitat structure, and 4) significant coastal zone development including highways that impacted inshore-offshore water exchange. Therefore, the effects of environmental conditions on recruitment are independent of fishery exploitation impacting the adult stock two to three years later (Fig. 6). Experimental studies in Florida confirm the negative effects of siltation (Marx and Herrnkind 1985b; Herrnkind and Butler 1986; Herrnkind et al. 1997), extreme salinity (Field and Butler 1994), and the loss of physical structure (Herrnkind and Butler 1986; Butler and Herrnkind 1997) on postlarval and juvenile lobster survival. Figure 5. Effects of dam construction and natural nutrient depletion in coastal regions and recruitment trend. Also, significant decrease of fertilizer use impacting anthropogenic induced nutrients to coastal areas (from Puga et al 2008). Figure 6. Significant decreasing trend in recruitment antecedes in 3 years the drop in exploitable population (Puga et al. 2008). In Florida, the effect of decreasing parent stock on trends |
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| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
