1. REPORT ON THE SPINY LOBSTER FISHERIES OF THE BAHAMAS

Lester Gittens and Michael T. Braynen^[7]

Description of the Fishery

There have been no changes of major significance to the fishery in recent years (see also Deleveaux and Bethel, 2001).

Management Regulations

No changes have taken place in regard to this. There have been some representations from some fishers to have the length of the closed season extended to cover all or parts of the months of March and September.

Biology

Three types biological analysis have been done on Bahamian spiny lobsters in recent times. These include a length-cohort analysis used since the mid 1990s, a length-converted catch curve analysis (FiSAT II) (completed September 2002) and a virtual population analysis. These were all based on export records of the commercial fisheries from the 1988/89 season through the 2001/2002 season. At the present time the length-cohort analysis method is considered the most accurate.

Length Cohort Analysis

The most recent fishing mortality rates indicate that the stock is close to being fully exploited having observed an increasing trend over the last twelve fishing seasons (Fig. 1) (Ehrhardt 2002).

Figure 1. P. argus seasonal average fishing mortality rates for sexes combined

The stock biomass abundance shows a declining trend. As a result stock biomass has decreased by 33 percent from 24 million pounds (11 793.4 tonnes) of tails in 1991/1992 to 16 million pounds (7 257.5 tonnes) of tails in 2001/2002 (Fig. 2). This, however, is expected as exploitation increases towards maximum production of 5,8 million lbs (2 630 8 tonnes) of tails under the present spatial distribution (Ibid).

Figure 2. P. argus population abundance and seasonal landings (Lb tails)

The trends in biomass stock abundance estimated from length cohort analysis are generally corresponding to the anomalies of the biomass abundance obtained through the application of a dynamic production model. These trends support the concept that the cohort analysis results are representative of the biomass dynamics experienced by the stock (Ibid).

Figure 3. Fishing mortality trends in The Bahamas using the length-converted catch curve method of FiSAT II

FISAT II Analyses

A new set of growth parameter estimates and mortality estimates was obtained for this updated report, using the ELEFAN I and Shepherd routines. A von Bertalanffy growth rate parameter estimate of K = 0.18 for males and females combined was obtained and used to obtain the mortality estimates using a length-converted catch curve method of FiSAT II. Sensitivity analysis revealed that K estimates were questionable and had a large effect on the mortality estimates. The mortality estimates are therefore uncertain but nevertheless of some value when determining relative changes and overall trends. Despite differences in the estimates of growth rate from this latest study compared to earlier studies of Deleveaux and Bethel (2001) and Ehrhardt (2002), both this analysis and the virtual population analysis using these estimates were consistent with the length cohort analysis in showing that there has been a gradual increase in mortality since the early 1990s (Fig. 3).

An interesting result from these FiSAT II analyses was that the length-converted catch curves produced mortality estimates that are significantly larger than those estimated from the earlier calibrated length cohort analysis of Ehrhardt (2002). Possible reasons for this discrepancy could be: a) that the FiSAT II analyses were based on both sexes combined, while the cohort analyses treated the sexes separately; b) the differences in growth parameters used in the analyses, as discussed above; or c) differences in the length frequency data generated for the analyses. Of these, the difference in the growth parameters is considered to be the most likely cause of the discrepancy.

Virtual Population Analysis

This method was applied for the first time at the present workshop and although still in progress of development it supports the conclusions of the other two assessment methods in that it has shown that there has been a gradual rise in fishing mortality. This method takes selectivity into account. The potential for further use of this method in support of the length-cohort analysis will be explored.

Sex Ratio

The sex ratio of males to females in samples between February 2000 and November 2001 was 1 373:1 265 or 1.00:0.92. This was significantly different from a 1:1 ratio (c² analysis, p = 0.035) thus indicating males were more abundant than females. This, however, may not be reflective of the true sex ratio in the wild since egg-bearing females would be absent from the lobsters sampled.

Available Data and Recent Developments

The previously reported difficulties in respect of fisheries catch and effort collection in The Bahamas still prevail. While recorded commercial catch figures are available for the entire country, catch and limited effort data are only recorded for several of the main fishing islands. Currently there is no fishery-independent data collected or supplied to the Department of Fisheries on a continuous basis on spiny lobsters in The Bahamas.

Average Size Trends

There has been a gradual decline in the average size of lobsters exported from The Bahamas since 1988/89 with the most recent complete season having the smallest average size on record (Fig. 4). Approximately 90 percent of landings are exported and therefore data from export can be considered reflective of what has been landed. Interpretation of average size trends is complicated by the decrease in minimum size that can be landed by law in 1995, the increased use of condominiums in shallow areas and changes in recruitment.

Figure 4. Average size of lobsters exported from The Bahamas (7.5 oz = 210 g)

Status of the National Spiny Lobster Resource

The data that has been collected over the last two decades indicate that both the weight and value of the total landings of whole lobster, converted from tail weight, have steadily increased and peaked at 9 023 tonnes (19.9 million lbs) in 2000 (Fig. 5). Landings were fairly stable for most of the analysis period. However, in 2001 there was a decline of 25.7 percent to 6 703 tonnes (14.8 million lbs). While the 2000 landings are the largest on record for The Bahamas, the sudden decrease in landings in 2001 is a cause for concern. This decrease may be explained by the decrease in abundance observed during the 2000/2001 season (Fig. 2) (Ehrhardt, 2002).

The largest difference between the same months of each year was between November 2000 and November 2001, where November 2001 landings were 46 percent lower than November 2000. Hurricane Michelle struck the Bahamas during November 2001 and has probably contributed to this difference in landings during this month. This was not the single factor however as February, March and April of 2001 had landings that were about 40 percent lower than the same months in 2000 and all months showed declines.

The comparison of landings between 2000 and 2001 should not be considered in isolation. There was a 35.4 percent decline in landings from 1985 to 1986, while on the other hand the 10 percent increase recorded between 1999 and 2000 was the largest increase in 10 years.

Review of the landings for January to March 2002 indicates that the decline appears to have been arrested but this cannot yet be attributed either to increased catchability due to weather or to changes in abundance.

Table 1. Total recorded spiny lobster landings in tonnes (converted to whole weight) and value in B$, The Bahamas (1982-2001) (B$1.00 = US$1.00)

Figure 5. Recorded weight of spiny lobster landed in The Bahamas (1982-2001)

Status of the Stock

The Department of Fisheries considers that the spiny lobster stocks in The Bahamas are still in good condition, however, concerns are raised by the reported decline in landings, abundance and mean size and the steadily increasing fishing mortality. The Department may soon be faced with the challenge of limiting catches in a fishery that has historically been hard to monitor and control.

Social and Economic Status and Importance of the Fisheries

Earnings by fishers

The commercial fishing industry makes a significant contribution to the country's economy. Fishing vessel owners and operators earned in excess of B$64,815 million through the harvesting of fishery resources during 2001.

Table 2. Summary of total recorded landings of marine products in The Bahamas by weight (tonnes) and value (B$), 2000-2001

The harvesting of spiny lobster is by far the most important commercial fishing activity in The Bahamas. During 2001, it contributed 48 percent by weight (tails weight) and 81.7 percent by value of the total recorded landings of fishery products in The Bahamas with a value of B$52.96 million. These recorded landing were a substantial decrease from those recorded in 2000, valued at $70.62 million (Table 2).

Prices paid to fishers increased only very slightly from 2000 to 2001, and the downturn in lobster landings in 2001 was primarily responsible for the 20 percent decline in monies paid to fishers when compared to the previous year. This marked decline was due, in part to the fact that landings in 2000 were particularly high. In spite of this apparent loss of income fishers appeared to make little of the issue.

Fishing Fleet

The number of commercial fishing vessels licensed by the Department of Fisheries, (those greater than 20 feet = 6 m in length) declined from 365 in 2000 to 320 in 2001, but up to 21 September 2002, 386 such vessels had been licensed. These fluctuations probably do not represent significant fleet changes but more likely reflect a casual attitude on the part of fishers to obtaining the required licence.

Export Marketing

The lobster continued to be the most important fishery product exported from The Bahamas. As a high demand for the lobster exports continued to be enjoyed, the two major markets continued to be the USA and France (Table 3). During the season 2001/2002 the market share of France declined to 34.2 percent as compared to 40 percent in the previous season.

Table 3. Lobster tail exports (weight, value) by destination

Conflicts

No resolution has been found for the conflicts that plague many commercial fishers. Fishers without the means, or desire, to invest in the construction of condominiums are accused of interfering with and stealing from those set by other fishers. Conversely, those without condominiums complain that others set their condominiums in so many areas that there is little space left for them to operate without coming in to the proximity of the condominiums. Because of the high value of the lobster some fishers guard their condominiums jealously and there have been violent confrontations over this issue.

Conclusions and Recommendations

The Bahamas has made recent progress in determining the state of its fishery although it is currently severely limited in the type of data it is currently able to collect and hence the types of analyses it can apply to its fishery. Renewed efforts must be made to explore ways to improve data collection as the information currently collected does not include some aspects of the biological, ecological, economic, and social data considered to be necessary to assist in the formulation of management strategies.

Other problems facing Bahamian fishers that need to be addressed relate to the controlled use of lobster condominiums and the illegal harvesting of lobsters by locals and foreigners. Also given the likelihood that the fishery is close to full exploitation the Department may soon be faced with the challenge of limiting catches in a fishery that has historically been hard to monitor and control.

The recommendations for the fishery include:

• Determine reference points according to management goals in order to give management something specific to work towards.

• Utilize regional funding to a larger extent e.g. CARICOM Fisheries Unit Funds.

• Obtain advanced training for staff so that they may develop appropriate assessment methods for the fishery and be better able to ascertain the benefits and limitations of current and newly developed methods.

• More support for regional cooperation and research, e.g. in the current CARIFORUM Fisheries Project.

• Explore the possibility of employing persons to deal strictly with data collection including going to sea aboard fishing vessels. This effort would have to have external support, i.e. from the industry (fishers and processors).

• Ensure that scientific and management staff are kept up to date on the latest research by travelling to major scientific and management conferences regardless of whether the Department has something to present. This will require external support.

• Make all possible efforts to reduce poaching. Some possibilities include improving prosecution of poachers, increasing penalties for poaching and having more coordinated approaches among government ministries and neighbouring countries.

• Collect data to determine when the peak of spawning with a view to possibly adjusting the closed season.

References

Cochrane, K.L. (ed). 2002. A fishery manager's guidebook. Management measures and their application. FAO Fisheries Technical Paper. No. 424. FAO, Rome, 231 p.

Deleveaux, V.K.W. & Bethel, G. 2001. National report on the spiny lobster fishery in the Bahamas. FAO Fishery Report No. 619: 161-167.

Ehrhardt, N.M. 2002. An assessment of the spiny lobster fishery in the Bahamas. Technical report presented to the Department of Fisheries, Government of the Bahamas.

DECISION MAKERS HIERARCHY FOR THE BAHAMIAN LOBSTER FISHERY

Decisions can be made at each level without consulting those higher in the hierarchy. The extent to which this is done depends on the magnitude of the decision.