The Pacific spiny lobster (Panulirus gracilis) is an important fishery resource from the Western Pacific region of Panama. Between October 2005 and April 2007, the Gulf of Montijo lobster population was sampled to determine total length (LT), cephalothorax length (LC), abdominal length (LA), total weight, sex, gonadal development, and frequency of gravid females. Furthermore, lobster landing volumes from the Gulf of Chiriquí National Marine Park were used to estimate the catch per unit effort (CPUE) (kg of lobster landed / fisherman-week) between 2000 and 2009. Lobster LT in the Gulf of Montijo (average ± SD) was 206 ± 31 mm and females were significantly larger in size and weight than males. The cumulative frequency of cephalothorax and abdominal lengths indicated that a high percentage of catches occur below the minimum legal size when regulation is applied measuring the abdomen (112 mm). Incidence of such cases is greater in males than in females. This difference might be a consequence of a regulation lacking morphometric data for P. gracilis and the assumption that the abdominal length is twice the cephalothorax length. Females with mature gonads and eggs were observed throughout the sampling period, which is indicative of continuous reproduction. Sex ratio was male biased (1.31:1). Between 2000 and 2009 there was an important reduction in volume and CPUE.

The common polychaete, Americonuphis reesei is used to stimulate the reproductive process of broodstocks lines in shrimp farms. In accordance, the Aquatic Resources Authority of Panama (ARAP) regulates concessions for the harvest at different locations of the Panamanian Pacific, including the Gulf of Montijo. This motivated the present study to characterize the status of this fishery resource under the work frame of the management plan for the resources of the Montijo Gulf wetland assemblage. Sampling campaigns were completed between March and October 2013 at the harvest sites to obtain samples and analyze size, weight, density and the catch unit effort (kg/tide∙fisherman). Data on the total catch by locality was also obtained from the ARAP registry alongside records from the local concessionary fishing company. The results indicate that the density of polychaetes is low, averaging 0.38 ind/m2 (SD = 0.39, n = 42). Total length averaged 72.86 cm (SD = 20.33, N = 30), while the total weight 32.21 g (SD = 13.75, N = 30). The extraction biomass has shown variation over time with the maximum during 2013 at 10588.00 kg, highly above the mean annual value between 2008 and 2013 at 5411 kg. The Catch per unit effort remained between 4 to 5 kg /tide∙fisherman in 2013 as well as for the period 2008 to 2011.