An important part of the fishing activity in Mexico is carried out in the coastal strip and has a strong social, economic and ecological importance. In the state of Guerrero, mollusks fishing is coastal and craftwork activity focused on a small number of species and without information on biology and reproductive or ecological aspects for most species caught. This research was carried out in the Costa Chica region, Guerrero, Mexico and the aims were: 1) To analyze the socioeconomic features of cooperative societies of fishing production; and 2) To know the diversity of mollusks caught by coastal fishing and the species that have the greatest importance in fishing. From February to April 2013-2015, seven fish coop units, four piers and places where seafood is sold were visited. For the socioeconomic analysis and the determination of the species that have more importance in the coastal fishing, a total of 67 surveys were applied. In order to determine the cast of species, the specimens captured by the fishermen were used, which were identified and counted. A total of 67 interviews were analyzed and an average of $1806.00 was estimated as weekly economic income just as a product of fishing, it was also estimated that on average the fishermen work 4.3 days a week. Fisheries cooperatives market most of their produce directly to restaurateurs and locals on the piers. Replacement of older adults by young fishermen from the same region was observed, most are adults between 22 and 39 years old. 25 species of mollusks of economic importance were registered for the coastal fishermen of the Costa

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Conus snails produce venoms containing numerous peptides such as the α-conotoxins (α-CTXs), which are well-known nicotinic acetylcholine receptor (nAChR) antagonists. Thirty-eight chromatographic fractions from Conus princeps venom extract were isolated by RP-HPLC. The biological activities of 37 fractions (0.07 µg/µL) were assayed by two-electrode voltage clamp on human α7 nAChRs expressed in Xenopus laevis oocytes. Fractions F7 and F16 notably inhibited the response elicited by acetylcholine by 52.7 ± 15.2% and 59.6 ± 2.5%, respectively. Fraction F7 was purified, and an active peptide (F7-3) was isolated. Using a combination of Edman degradation, mass spectrometry, and RNASeq, we determined the sequence of peptide F7-3: AVKKTCIRSTOGSNWGRCCLTKMCHTLCCARSDCTCVYRSGKGHGCSCTS, with one hydroxyproline (O) and a free C-terminus. The average mass of this peptide, 10,735.54 Da, indicates that it is a homodimer of identical subunits, with 10 disulfide bonds in total. This peptide is clearly similar to αD-CTXs from species of the Indo-Pacific. Therefore, we called it αD-PiXXA. This toxin slowly and reversibly inhibited the ACh-induced response of the hα7 nAChR subtype, with an IC50 of 6.2 μM, and it does not affect the hα3β2 subtype at 6.5 μM.

Scutellastra mexicana is the largest species of giant limpet in the world. This species is distributed along the tropical Mexican Pacific and is now considered extinct in some areas of the region. In prehispanic Mexico, this limpet was used for food, ornamentation, and in mortuary offerings. More recently, its meat has been highly valued for human consumption. During the 1970s and 1980s, overexploitation of this resource caused the population to decrease drastically. This study is a report on the population status of the giant Mexican limpet S. mexicana on the Mexican Pacific coast. Free divers explored the rocky southern coast of Jalisco, Mexico, for the presence of specimens. A total of 404 limpets were identified at 18 sampling sites. Their density was estimated to be 0.0012 limpets/m2 with a catch per unit effort of 7.6 limpets/dive hour. Limpet sizes ranged from 5.0 to 23.3 cm in length and from 3.8 to 20.7 cm in width, with a mean shell length of 13.4 cm. Currently, S. mexicana is under special protection by Mexican laws. However, this species is not listed as endangered by any international wildlife protection and conservation group. This may be due to the lack of information on this species' population dynamics over time in the Mexican Pacific and the lack of interest in this mollusc since it is a non‐charismatic species.

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A study using a mark-recapture method was used in order to estimate the abundance and population structure of the Purple snail Plicopurpura pansa (Gould, 1853), on a rocky shore in Tenacatita Bay, Jalisco, Mexico. A comparison of the results obtained by this method and the linear transects parallel to coast was performed, the latter has been the method most commonly used in previous studies for this species. The results indicate significant differences in estimates of population parameters obtained by the two methods used; we found that in a general of linear transection methods tend to underestimate the abundance of these snails. Given the implications of these findings for the management of a species with potential for exploitation, such as the Purple snail, we discuss the possible causes and significance of this discrepancy of the methods.

Symbiosis between decapods and mollusks provides a unique opportunity to examine some of the evolutionary strategies employed by marine invertebrates. We describe the sexual and reproductive traits of the pearl oyster shrimp, Pontoniamargarita Verril, 1869, found symbiotically inhabiting the mantle cavity of the rugose pen shell, Pinnarugosa Sowerby, 1835. Solitary males and females (ovigerous and non-ovigerous) and heterosexual pairs (with ovigerous and non-ovigerous females) were found in a total of 47 rugose pen shells collected from a sandy area with seagrass meadows on the southeastern coast of the Gulf of California, Mexico. The body length (BL) of female P.margarita was correlated with the shell volume of their rugose pen shell host. The sex ratio was female-biased (0.85M:1F). Female P.margarita were larger than their male counterparts in terms of BL, cephalothorax length (CL), and the maximum chelae length of the second pereopod (MCL). The CL and MCL were more strongly correlated for males (r = 0.70, p = 0.01). The number and volume of eggs per ovigerous female varied from 95 to 1,571 and from 5.46 ± 0.48 to 8.85 ± 0.97 mm3, respectively. Our results indicate polygamous behavior and social monogamy among P.margarita, and a short-term pairing system for their association with P.rugosa.