Species Composition, Relative Abundance, Distribution, and Size Structure of Spiny Lobsters (Panulirus spp.) in Eastern Visayas, Philippines

Abstract

Spiny lobsters are an important resource of the artisanal fishery in Eastern Visayas, Philippines. It has long been harvested and contributes to the region's local economy. Despite being a high-value species, the spiny lobster resource has not been monitored and regulated for decades. This study aimed to assess the spiny lobsters in Eastern Visayas and provide recent information to support local resource management. Spiny lobsters were assessed from 2018 to 2019 in four major sampling areas in Eastern Visayas: (1) Guiuan and (2) San Policarpo in Eastern Samar province, (3) San Jose in Northern Samar, and (4) Silago-Hinunangan in Southern Leyte. Species composition, relative abundance, geographical and seasonality distribution, and size structure of spiny lobster resource in the region were described. Six species and subspecies of the genus Panulirus were observed in the catch landings: P. penicillatus (65%), P. ornatus (18%), P. versicolor (2.8%), P. femoristriga (5.3%), P. longipes longipes (6.1%), and P. longipes bispinosus (1.7%). Incidental catches (1.3%) of the ambiguous forms of P. longipes were also observed. P. penicillatus were more prevalent in areas exposed to the Pacific, such as Guiuan and San Policarpo, while adult P. ornatus were chiefly harvested in Northern Samar and Southern Leyte. The other lobster species were either occasional or rare in some areas. Calmer waters and good weather during dry months in Eastern Visayas allow fishers to sail and gather lobsters. The surge in the abundance of P. ornatus and P. penicillatus from July to December was also affected by market demand. Panulirus femoristriga, P. versicolor, and P. longipes subspecies generally peaked from April to June in Eastern Samar and July to September in Northern Samar and Southern Leyte areas. These species would decline in abundance towards the end of the year. The general size structure of spiny lobster catches in Eastern Visayas revealed extreme harvesting of juveniles and sub-adults (< 77.5 mm CL), except for P. ornatus. The fishery could be on the verge of growth overfishing since 50-90% of the catch have CL below their size at first maturity. Panulirus ornatus is targeted at larger sizes (96–107 mm CL) and as a live catch due to its high value and marketability. Raising awareness of the species, reinforcing existing regulations on minimum size limits, and prohibiting the use of compressor diving as a hazardous collection method should be prioritized by fishery managers to protect both the spiny lobster resource and the gatherers in Eastern Visayas.