10 Squat lobster fisheries

10 Squat lobster fisheries Ingo S. Wehrtmann and Enzo Acuña

ABSTRACT

INTRODUCTION

Squat lobsters can be found worldwide, often in high abundance, which makes them a potentially commercial fishery resource. Despite this favourable situation, well-established fisheries are currently found exclusively in Latin America, especially in Chile. Other countries (Argentina, Mexico, New Zealand) have intensively studied the ecology of squat lobsters and recognised their potential as a fishery resource but, for various reasons, no commercial exploitation has been implemented so far. We compiled available information about target species, fishing methods, fishery statistics and management as well as by-catch of squat lobster fisheries in Central American countries and Chile. Target species are Pleuroncodes monodon and P. planipes in Costa Rica, El Salvador, Nicaragua and Panama, and in Chile, P. monodon and Cervimunida johni. Finally, we present a brief compilation of information about squat lobsters in other countries, where these decapods are recognised as a potential fishery resource.

Decapod crustaceans represent a highly appreciated and valuable fishery resource. International crustacean exports increased between 1987 and 2007 from 1 673 820 to 4 520 848 tonnes (t) (FAO 2009). During the same period, the value of these exports more than doubled, reaching in 2007 a value of US$20.6 billion (FAO 2009). Owing to the progressive depletion of coastal marine resources, fishing expanded into offshore areas and deeper waters (Morato et al. 2006; Pauly et al. 2005), a trend that has also been observed in the exploitation of decapod resources (Arana et al. 2009). Squat lobsters have a worldwide distribution (Schnabel et al. 2011, ch. 5 this volume) and play an important role in the marine food chain of coastal marine zones (Bernard et al. 1985; Lovrich and Thiel 2011, ch. 6 this volume; Markaida 2006; Preti et al. 2004; Stewart et al. 1984; Torres-Rojas et al. 2010; Villarroel and Acuña 2000). However, well-established commercial fishing for species of Munididae (the family to which the commercial species now belongs, Ahyong et al. 2010) is restricted to Latin America, especially to Chile (Bahamonde et al. 1986; Roa and Bahamonde 1993). Munidids, usually referred to in older literature as galatheids, are fished for human consumption, but

KEYWORDS Pleuroncodes, Cervimunida, fishery, management, Chile, Costa Rica, El Salvador, Nicaragua, Panama.

© Museum Victoria, Australian Museum, and Dr Gary C.B. Poore 2011 Published by CSIRO Publishing, http://www.publish.csiro.au/

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The Biology of Squat Lobsters

squat lobster meal is also important as an ingredient in feeding cultured shrimp (Villarreal-Colmenares 1995; Villarreal et al. 2006) and fish food (Ellis 1979; Spinelli and Mahnken 1978; Vernon-Carter et al. 2001). Squat lobsters are a source of natural astaxanthins that serve as pigmentation, both in the final growth phase of cultured salmon and trout (Villarreal-Colmenares 1995) and during production of chicken eggs (Carrillo-Domínguez et al. 1995). A proteolytic enzymatic extract from P. planipes may help accelerate the maturation of cheese (García-Carreño and Hernández-Cortés 1995). Chitosan hydrogels based on P. planipes shells are considered to have potential for various applications in biomedicine, especially in surgery and repairing damaged tissue (Sánchez et al. 2007). This chapter compiles information on bottom trawl squat lobster fisheries of the world; as far as we know, there is no commercial pelagic squat lobster fishery. It is organised by region: Central America, South America and other areas where squat lobsters are commercially harvested. For each fishery, we present the target species, describe fishing methods (the art of the fishery), provide, whenever possible, information on fishery statistics and management strategies, and summarise the results of by-catch studies. In many cases, gathering such information has been difficult; we cannot exclude the possibility that some unpublished data have not been included. We worked with official fishery statistics, i.e. data presented by the fishers to authorities, which do not necessarily adequately reflect actual catches. In this context, it is worth mentioning that industrial squat lobster landings in Chile have been certified since 2005 by an independent agency appointed by the government. The aim of the present study was to describe possible trends, not to evaluate the accuracy of the official fishery statistics.

SQUAT LOBSTER FISHERIES IN CENTRAL AMERICA Target species Two species of squat lobsters are of commercial interest in Central America: Pleuroncodes planipes Stimpson, 1866 and P. monodon (H. Milne Edwards, 1837). The geographic distribution of the former ranges from San Francisco (37°N) in California throughout the

Gulf of California, Mexico to Central America (Hendrickx and Harvey 1999). Pleuroncodes monodon has been reported from the Gulf of Tehuantepec, Mexico, and from Peru to Chile (Bianchi 1991; Longhurst 1967). The governmental fishery agency in El Salvador (CENDEPESCA) indicates both P. monodon and P. planipes in its annual reports, but when mentioning official landings of commercially exploited species refers exclusively to P. planipes (e.g. CENDEPESCA 2004). However, the local name used in the annual reports is ‘langostino chileno’, the name applied to P. monodon. According to Bianchi (1991), the population off Central America is in fact P. monodon and the species name, P. planipes, has been erroneously used for specimens obtained in that area. This conclusion was corroborated by results of recent studies carried out with squat lobsters currently fished off Costa Rica: preliminary molecular-genetic analyses of specimens obtained from the deep-water shrimp fishery confirmed that the species is P. monodon (E. Macpherson, unpub.). There is thus a great deal of confusion regarding the taxonomic status of commercial catches of Pleuroncodes in the Central American region. Additional studies are needed to clarify the species identification and to document possible geographical overlap of the two species in Central America. Commercial squat lobster fishery in Central America Both Pleuroncodes species are present in Central America, but are not the target of a commercial fishery in all countries in the region. Bianchi (1991) analysed the demersal assemblages of the continental shelf and slope edge along the Pacific coast between Mexico and northern Costa Rica. He reported high densities of P. monodon off the coast of Nicaragua and El Salvador, reaching maximum values of 20 t h-1. According to a recent study of the macroeconomic indicators of the fishery sector in Central America, between 2000 and 2007 (OSPESCA 2009), squat lobsters have been fished commercially in Nicaragua and Panama as well as in El Salvador (CENDEPESCA, annual reports). Figure 10.1 depicts the squat lobster production in these three countries. The most conspicuous feature is the enormous increase of squat lobster production in 2007 and 2008 in Nicaragua (see below for further details).


10 – Squat lobster fisheries

Figure 10.1: Squat lobster production in Panama, Nicaragua and El Salvador, 2000–08 (2008 data available only for Nicaragua).

El Salvador An exploratory fishery for squat lobsters started in El Salvador in 1978–79, and the resource became commercially exploited in 1980 and 1981 (N.R. Hernández, pers. comm.). However, commercial landings of squat lobsters started to be mentioned only in 1993 (as squat lobster production, which is not the same as ‘landings’) in the annual reports of the government fishery agency, Centro de Desarrollo de la Pesca y la Acuicultura (CENDEPESCA) of the Ministry of Agriculture and Animal Husbandry (MAG). Production was low during the following years (until 1996), between 9 tonnes and 20 tonnes per year (t y-1). Subsequently (1997–2000), squat lobster catches disappeared completely from the annual reports. The commercial exploitation of this resource in El Salvador resumed in 2001 on a substantially higher level than previously and reached 13 708 t in 2005, the highest annual landings (since 2001 indicated in the annual reports as ‘landings’) so far recorded. In 2007, landings attained 11 377 t y-1; thereafter, no more data have been published. According to F. Chicas (Universidad de El Salvador, pers. comm.), commercial squat lobster exploitation started to decline in 2008, and in 2009 the main fishing company closed its squat lobster fishing operations in El Salvador.

Squat lobsters were exported from El Salvador as frozen products and as squat lobster meal. Annual statistics for 2001 and 2003 included 124 t of chitin and 214 t of chitosan as squat lobster products. It is assumed that these products were combined and termed ‘squat lobster meal’ in subsequent reports. This product was exported to Asia, Europe and North and South America; during 2005–07 it was exported almost exclusively to South America (probably for the production of salmon feed). The highest value of squat lobster meal exports was reached in 2006, with US$606 798. The importance of squat lobsters in the fishery of El Salvador becomes evident when analysing published landings of demersal resources (including different types of benthic shrimp, utilised by-catch and squat lobsters) during 2001–07. When the squat lobster fishery resumed in 2001, squat lobsters comprised 35% of all landings of demersal resources. This value increased continuously during the following years, reaching its highest value in 2005 with 98%. Commercial exploitation of squat lobsters in El Salvador was limited to two companies (three in 2004). Fishing operations were carried out by 10–13 trawlers but in 2002 only five boats were operating. The importance of the squat lobster fishery is reflected in an increasing fishing effort. Both fishing days and


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number of trips increased substantially during 2001– 06. While CENDEPESCA reported for 2001 a total of 125 fishing days with 64 trips, the most intense fishing operations occurred in 2005 with 2168 fishing days and 1007 trips. There is scattered information about the by-catch in the squat lobster fishery in El Salvador. The results of a stock assessment carried out during three months in 2007 showed surprisingly low mean by-catch rates, varying between 16% and 22% of the total catch by weight; these data are based only on hauls containing squat lobsters (Anonymous 2007). The values from 2007 are slightly lower than those obtained for 2003– 06 (average of 27% of by-catch, Anonymous 2007) and 2004 (average of 28% of by-catch, Cardenas-España and Orellana-Rugamas 2005). The by-catch fauna is highly diverse and includes 60 species, mostly fishes (67%), crustaceans (23%) and other species (10%) (Anonymous 2007). Several studies have provided information about squat lobster biomass along the coast of El Salvador. During the early 1980s, the CPUE was roughly 2000 kg h-1 in depths ranging from 90 m to 250 m (López 1982). A more recent study (Cardenas-España and Orellana-Rugamas 2005) revealed that the squat lobster catch rates increased from 140 m to 180 m but in deeper waters were significantly lower. The same authors demonstrated highly variable values of CPUE in different fishing zones and months. Highest average values per study zone were around 1500 kg h-1, while the CPUE based on individual hauls reached up to 2971 kg h-1. Stock assessments carried out in 2007 along the entire coast of El Salvador (Anonymous 2008) showed monthly mean CPUE between 595 kg h-1 (July 2007) and 2402 kg h-1 (November 2007); the highest individual CPUE was 4236 kg h-1 (November 2007). Costa Rica At least 15 galatheoid species have been reported from Pacific Costa Rica, most of them species of Munida and Munidopsis from deeper waters (typically below 150 m, Wehrtmann et al. 2010). Squat lobsters, especially species of Pleuroncodes, are the most common and abundant species in the by-catch of commercial deep-water shrimp fishery (Wehrtmann and Echever-

ría-Sáenz 2007; Wehrtmann and Nielsen-Muñoz 2009). Large individual catches (>1000 kg h-1; Fig. 10.2) may comprise exclusively Pleuroncodes (I.S. Wehrtmann, unpub.). However, trawler captains are not interested in this resource and discard all squat lobsters; in fact, they try to avoid areas with dense aggregations because squat lobsters clog the nets. Wehrtmann et al. (2010) reported the presence of P. monodon between 150 m and 350 m; this species was especially abundant below 240 m. The local shrimp trawlers (Fig. 10.3), typically equipped with two lateral nets, range in length from 16 m to 24 m, are powered on average by a 300 hp engine and usually have a crew of four to six. A description of the trawling nets and other technical details of the Costa Rican semi-industrial shrimp fishery fleet can be found in Bolaños (2005). Research cruises (August 2008 and May 2009) carried out with commercial shrimp trawlers covering the entire Pacific coast in the framework of the project PUEDES (http://puedes.csuca.org/) provided an excellent opportunity to study the status of this resource in Costa Rica (Hernáez 2010; Hernáez and Wehrtmann 2011; Wehrtmann et al. 2010). The results revealed that male Pleuroncodes reached significantly larger average sizes (28.2 ± 2.21 mm CL) than females (26.2 ± 1.78 mm CL). These sizes are similar to those reported from the squat lobster fishery in El Salvador (Cardenas-España and Orellana-Rugamas 2005; Anonymous 2007) and lower than those indicated for the Chilean squat lobster fishery (Roa and Tapia 1998). The distribution of the squat lobster biomass (Hernáez 2010) was highly variable, substantially higher during the rainy season (average of 713 kg km-2) than during the dry season (average of 16.0 kg km-2). These findings support the conclusion that squat lobsters are a neglected but potential fishery resource for commercial exploitation and would contribute to a diversification of the ongoing deep-water fishery along the Pacific coast of Costa Rica. Nicaragua The squat lobster, Pleuroncodes planipes, as indicated in the more recent fishery statistics of the Instituto Nicaragüense de la Pesca y Acuicultura (INPESCA),



Figure 10.2: Squat lobsters (Pleuroncodes monodon) as by-catch of the commercial deep-water shrimp fishery in Costa Rica. The photo shows the content of one of the two nets; the total catch of this particular haul was 1.2 t in 20 minutes (November 2004).

was not commercially fished in Nicaragua before 2003. Several stock assessments carried out between the 1970s and 1990s suggested a fishery potential of 50 000–85 000 t y-1 (Gutiérrez García 2003). Nevertheless, the squat lobster resource remained practically untouched. The situation began to change when shrimp landings declined significantly, which forced the government to impose a temporary fishing ban (April–May). As a consequence, the fishing sector in Nicaragua started to exploit the squat lobster resource; in 2003 INPESCA reported squat lobster landings for the first time (61 t). The landings decreased in 2004 and disappeared in 2005 from the annual report. In 2006, Nicaragua reported 343 t, and annual squat lobster landings increased drastically in 2007 and

2008 with 2696 t and 2868 t, respectively (Fig. 10.1). This increase was reflected in a concomitant increase in the number of fishing days. INPESCA reported 167 days of squat lobster fishing for 2005; for 2007, this value more than quadrupled (775 fishing days). According to INPESCA, the dramatic increase was due to the closure of the coastal shrimp fishery in 2007. The shrimp trawlers started fishing squat lobsters and the number of operating boats increased from one (2003–06) to five in 2007 and four in 2008. An assessment of the squat lobster stock along the Nicaraguan Pacific coast carried out in 2003 provided information about this resource before commercial exploitation started (Gutiérrez García 2003). The study reported an overall CPUE of 764 kg h-1. Highest


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Figure 10.3: Typical commercial shrimp trawler from Costa Rica, Central America.

fishing yields were obtained in depth ranges of 150– 200 m and 200–250 m, depending on the study zone. Males were on average larger than females (41.2 versus 37.6 mm CL). The total landings of the 77 hauls comprised 77.9% squat lobsters (according to the author, P. planipes), while the by-catch accounted for 21.1%. The fauna of the by-catch was principally composed of different crustaceans (Squillidae, Calappidae) and flat-fishes (Paralichthyidae) and, to a smaller degree, different molluscs and other fish species. To the best of our knowledge, results of more recent assessments are not available. It would certainly be interesting to assess the impact of the heavy exploitation at least during 2007 and 2008 (Fig. 10.1) on the squat lobster resource in Nicaragua. Panama The available data for Panama (2000–07) indicate a relatively constant commercial squat lobster production, from 713 t in 2005 to a maximum of 1022 t in

2001 (Fig. 10.1). The overall contribution of squat lobster production to industrial marine fisheries in Panama during this period was 0.3% (OSPESCA 2009). Squat lobsters are also exploited by the local artisanal fishery. Production was low in 2000 and 2001 (64 t and 41 t, respectively) but in subsequent years production increased continuously, reaching 492 t in 2008.

SQUAT LOBSTER FISHERIES IN CHILE Two species of squat lobsters of the family Munididae, Cervimunida johni and Pleuroncodes monodon, are harvested commercially off Chile. The commercial fishery for squat lobsters began in 1953 as they started to become important in bottom trawl catches of the hake Merluccius gayi in central Chile (Arana et al. 1994). The fishery started exploiting the yellow squat lobster C. johni, based entirely on landings made at the ports of Coquimbo, Valparaíso and San Antonio (Bahamonde et al. 1986). Landings



peaked in 1965, but drastically decreased to one-fourth in 1970. Later the fishery expanded southwards, harvesting the red squat lobster P. monodon, beginning in 1966 off San Antonio (33°35΄S), and extending to Talcahuano (37°S) (Bahamonde et al. 1986). These fisheries are bottom trawl fisheries that take place close to the shelf break and into the upper slope, between approximately 180 m and 500 m depths. The red squat lobster is fished in shallower waters (