Análisis de la pesquería de la langosta Panulirus gracilis (Streets, 1871) en la zona de Santa Cruz, Guanacaste, Costa Rica
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2009-10
Autores
Naranjo Madrigal, Helven
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Universidad Nacional (Costa Rica)
Resumen
Se realizó un estudio de la pesca artesanal de la langosta P.gracilis en Santa Cruz, Guanacaste, con el fin de conocer el estado actual de dicho recurso pesquero e integrando algunos indicadores bio-económicos. En esta región se utilizan dos modalidades de extracción: buceo a pulmón y buceo con compresor; y un único arte de pesca (bichero) de gran versatilidad y que permite capturar otras especies de interés comercial. Los tres puertos bajo estudio producen altos rendimientos en la captura de langosta y de otra gran variedad de especies bentodemersales lo que señala el carácter multi-específico de esta pesquería. Un porcentaje importante de estas capturas es utilizado para consumo alimenticio por los pobladores de las comunidades. El índice de captura por unidad de esfuerzo (CPUE) mensual en áreas someras asociada a la modalidad de pesca del buceo a pulmón se vio afectada por la actividad extractiva del buceo con compresor que también opera en áreas de poca profundidad y además podría estar alterando patrones de movimiento de la langosta desde áreas profundas hacia la costa. El indice de capturabilidad (q) sugiere una mayor disponibilidad de langosta en áreas someras en julio, agosto y octubre.
El análisis de algunos parámetros biológico-pesqueros de los 843 especímenes de langosta capturados entre noviembre del 2007 y octubre del 2008 mostró que gran parte del esfuerzo pesquero esta ejerciendo fuerte presión sobre langostas por debajo de la talla mínima legal (80 mm de LC) y que comprendieron el 74,9% de las capturas. Las longitudes cefalotoráxicas de los ejemplares estuvieron comprendidas entre 42,8 y 143,6 mm para machos y entre 35,8 y 115 mm para hembras. La estructura de tallas muestra un considerable solapamiento de segmentos poblacionales y el incremento de las tallas con la profundidad en donde operan las dos modalidades de pesca estudiadas. El porcentaje de machos fue mayor con un 57,6% y las hembras con un 42,3% con respecto al total de la población muestral. La relación entre LC y peso reveló que las hembras pesan más que los machos de una misma talla y que esta diferencia fue significativa (p < 0,05). Mediante el índice de actividad reproductiva (IAR) se determinó un patrón reproductivo que inicia en abril y continua hasta agosto propiciado por un aumento en la temperatura del océano a partir de marzo. Utilizando diferentes metodologías se determinó que la talla de madurez sexual en hembras se encuentra entre los 62,4 y 76 mm de LC que alcanzarían a una edad aproximada de 2,1 años. Los parámetros de crecimiento de Von Bertalanffy para machos y hembras (K=O,38 - 0,45; 121,7 — 166,9) mostraron un crecimiento acelerado en comparación a otras especies. Los machos por su parte exhibieron una mayor tasa de crecimiento que las hembras. Además, la mortalidad natural (M), la mortalidad total (Z) y la mortalidad por pesca (F) fue mas alta en machos (0,49 - 2,34 - 1,92) que en hembras (0,47 - 1,82 — 1,42). El reclutamiento para ambos sexos presentó un comportamiento continuo durante el año con un pulso de mayor intensidad en julio de 18,5%. Bajo el actual régimen de pesca la población parece estar en riesgo de colapso según lo indica la alta tasa de explotación (E) de 0,80.
La captura de la langosta P.gracilis en Playa Lagarto resultó ser el recurso mejor pagado y generó ingresos que superaron los 48,4 millones de colones para el buceo con compresor y 4,4 para el buceo a pulmón. Los ingresos totales por concepto de langosta y demás especies superaron los 100 y 10 millones de colones para el buceo con compresor y el buceo a pulmón, respectivamente. Para la modalidad de pesca con compresor los costos totales ascendieron a aproximadamente 29,5 millones y para el buceo a pulmón a 2,6. De esta forma se obtuvo una renta anual de 77,7 millones para ambas modalidades. El buceo con compresor resultó ser ligeramente más rentable y con mayores costos operacionales que el buceo a pulmón y además para éste es económicamente ineficiente capturar solo langosta debido al estado de sobreexplotación que presenta este recurso. Por otra parte, se obtuvo una renta promedio por viaje de pesca para ambas modalidades de 14 mil colones. Además, en esta pesquería se evidenció el carácter de acceso abierto y el uso no sustentable de los recursos 10 que ha Ilevado a la condición de la "tragedia de los cornunes" que explica que existan costos de exclusión y externalidades negativas que están afectando los ingresos de los usuarios.
The lobster P.gracilis artisanal fishery in Santa Cruz, Guanacaste was investigated in order to know the current state of this resource, in combination with various bioeconomic factors. In the Guanacaste region there are two styles of fishing: the first being lung diving and the second "hooka" (using a compressor). The divers use a unique tool called "bichero" that also allows them to capture other commercial interest species at the same time. The three ports under study produce high yields of lobster catch and other varieties of bento-demersals species which indicates the multi-specific nature of this fishery. A significant percentage of the catch is used for food consumption among the coastal community's residents. Monthly capture per unit of effort index (CPEU) from shallow areas associated with lung diving operations was additionally affected by extractive "hooka" activities in the same areas. This trend could be altering lobster movement patterns from deep areas through to the coast. The catchability index (q) showed an increase in the lobster availability in shallow areas in July, August and October. The analysis of some biological parameters from 843 lobster specimens between November 2007 and October 2008 indicated that fishing effort is putting heavy pressure on lobsters below the legal minimum size (80 mm CL) that compose 74.9%. Specimen's carapace lengths varied among 42.8 and 143.6 mm for males and 115 and 35.8 mm for females. The size structure shows a wide overlapping of population segments, and a trend to increase with depth where lung diving and "hooka" diving operations function. The percentage of males was higher with 57.6% and females with 42.3% from the total population sample. The relationship between weight and LC revealed that females are heavier than males from the same size and this difference was significant (p <0.05). By the reproductive activity index (RAI) it was determined that a pattern beginning in April and continuing through August was prompted by an increase in the ocean temperature in March. Using different methodologies we established the size of sexual maturity in females among 62.4 and 76 mm LC reaching an appo (imate age of 2.1 years. The Von Bertalanffy growth parameters for males and females (K = 0.45 - 0.38; LC = 166.9 - 121.7) showed accelerated growth compared to other species. Males had a higher growth rate than females. Furthermore, natural mortality (M), total mortality (Z) and fishing mortality (F) was higher in males (0.49 - 2.34 - 1.92) than in females (0.47 - 1.82 - 1.42). Recruitment for both sexes presented a continued performance during the year with an elevated intensity pulse of 18.5% in July. Under the current fishing regime the population could be at risk as indicated by the high exploitation rate (E) 0.80. Lobster captures in Playa Lagarto were the best paid resource. The lobster fishing activity generated incomes of over 48.4 million colones for hooka diving and 4.4 million colones for lung diving. Total incomes for lobster and other species combined exceeded 100 million and 10 million colones for hooka diving and lung diving, respectively. For hooka total costs amounted to approximately 29.5 million and for lung diving 2.6 million. By this way, there was an annual income of 77.7 million for both. Hooka diving was slightly more profitable despite higher operational costs than lung diving. It is economically inefficient for the divers to catch only lobster because of the current overexploited state of this resource. We obtained an average income per fishing trip for both diving modalities of 14.000 colones. The study of this fishery revealed an open access condition and the unsustainable use of resources which has led to the state of the "tragedy of the commons" that explains why there are exclusion costs and negative externalities that affect user's revenues.
The lobster P.gracilis artisanal fishery in Santa Cruz, Guanacaste was investigated in order to know the current state of this resource, in combination with various bioeconomic factors. In the Guanacaste region there are two styles of fishing: the first being lung diving and the second "hooka" (using a compressor). The divers use a unique tool called "bichero" that also allows them to capture other commercial interest species at the same time. The three ports under study produce high yields of lobster catch and other varieties of bento-demersals species which indicates the multi-specific nature of this fishery. A significant percentage of the catch is used for food consumption among the coastal community's residents. Monthly capture per unit of effort index (CPEU) from shallow areas associated with lung diving operations was additionally affected by extractive "hooka" activities in the same areas. This trend could be altering lobster movement patterns from deep areas through to the coast. The catchability index (q) showed an increase in the lobster availability in shallow areas in July, August and October. The analysis of some biological parameters from 843 lobster specimens between November 2007 and October 2008 indicated that fishing effort is putting heavy pressure on lobsters below the legal minimum size (80 mm CL) that compose 74.9%. Specimen's carapace lengths varied among 42.8 and 143.6 mm for males and 115 and 35.8 mm for females. The size structure shows a wide overlapping of population segments, and a trend to increase with depth where lung diving and "hooka" diving operations function. The percentage of males was higher with 57.6% and females with 42.3% from the total population sample. The relationship between weight and LC revealed that females are heavier than males from the same size and this difference was significant (p <0.05). By the reproductive activity index (RAI) it was determined that a pattern beginning in April and continuing through August was prompted by an increase in the ocean temperature in March. Using different methodologies we established the size of sexual maturity in females among 62.4 and 76 mm LC reaching an appo (imate age of 2.1 years. The Von Bertalanffy growth parameters for males and females (K = 0.45 - 0.38; LC = 166.9 - 121.7) showed accelerated growth compared to other species. Males had a higher growth rate than females. Furthermore, natural mortality (M), total mortality (Z) and fishing mortality (F) was higher in males (0.49 - 2.34 - 1.92) than in females (0.47 - 1.82 - 1.42). Recruitment for both sexes presented a continued performance during the year with an elevated intensity pulse of 18.5% in July. Under the current fishing regime the population could be at risk as indicated by the high exploitation rate (E) 0.80. Lobster captures in Playa Lagarto were the best paid resource. The lobster fishing activity generated incomes of over 48.4 million colones for hooka diving and 4.4 million colones for lung diving. Total incomes for lobster and other species combined exceeded 100 million and 10 million colones for hooka diving and lung diving, respectively. For hooka total costs amounted to approximately 29.5 million and for lung diving 2.6 million. By this way, there was an annual income of 77.7 million for both. Hooka diving was slightly more profitable despite higher operational costs than lung diving. It is economically inefficient for the divers to catch only lobster because of the current overexploited state of this resource. We obtained an average income per fishing trip for both diving modalities of 14.000 colones. The study of this fishery revealed an open access condition and the unsustainable use of resources which has led to the state of the "tragedy of the commons" that explains why there are exclusion costs and negative externalities that affect user's revenues.
Descripción
Naranjo Madrigal, H. (2009). Análisis de la pesquería de la langosta Panulirus gracilis (Streets, 1871) en la zona de Santa Cruz, Guanacaste, Costa Rica. [Tesis de Maestría]. Universidad Nacional, Heredia, Costa Rica.
Palabras clave
PESCA, FISHING, LANGOSTA, LOBSTER, PESQUERIAS, ESPECIES, COSTA RICA