Jorge S. Ramírez-Pérez

Seasonal changes of progesterone and testosterone concentrations throughout gonad maturation stages of the Mexican octopus, Octopus maya (Octopodidae: Octopus)

Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya from Sisal in Yucatan State, Mexico, were investigated by radioimmunoassays and in relation to four gonad maturation stages (GMS) and to the reproductive cycle, as represented by two maturity indices (microscopic ‘MiMI’ and macroscopic ‘MaMI’). According to the GMS and the maturity indices, the reproductive season of O. maya from Yucatan occurred from February to June. In females, P4 and T displayed the same pattern, with a tendency to increase at the same time, although on average, P4 had seven-fold higher concentrations than T. In contrast, P4 and T in male gonads displayed a different pattern, where T concentrations were relatively stable throughout all of the study months. In the female gonad P4 was lowest (close to 0 pg g–1) during both developing (GMS-I) and maturing (GMS-II) stages, and increased (189 ± 53 pg g–1) approaching the mature stage (GMS-III) to a maximum value of 611 pg g–1. Concentrations of T in the male gonad were lowest (106 ± 9 pg g–1) during the maturing stage (GMS-II) and increased up to the mature stage (GMS-III), reaching a maximum of 440 pg g–1. Pearsons correlation (r) between hormones and maturity indices showed strong relationships for females (around 0.4 and −0.7; p < 0.05), but there were negligible or weak relationships for males (0.2 and −0.1; p > 0.05). Hormone correlations in females were inverse with MaMI and direct with MiMI. Our major findings showed that gonadal P4 levels were elevated during GMS-III and GMS-IV (i.e. periods of vitellogenic oocytes), where the characteristic aspect is an ovary with very high oocyte diameters, with the primary follicle cells deeply infolded in the ooplasm for yolk synthesis. These results suggested a synchrony between P4 and the process of folliculogenesis, and in turn, vitellogenesis.

Population structure and reproductive behavior of Sinaloa cichlid Cichlasoma beani (Jordan, 1889) in a tropical reservoir

The population structure and reproductive condition of the Sinaloa cichlid Cichlasoma beani from samples obtained from June 2000 to July 2001 were determined. Samples in the first week each month from the largest trader of tilapia in the Aguamilpa Reservoir in Mexico and were caught in gillnets (9.6 and 11.4 cm stretch-mesh size). Of 596 specimens, there were 427 males and 169 females; monthly sex ratio, frequency of lengths by the multinomial distribution, timing of reproduction, condition index, and size at first maturity was determined. Differences in the sex ratio and monthly totals were significant, favoring males, except for September 2000 and March 2001. From one (August 2000) to three modal groups (July 2000 and June 2001) were identified by size. There were no significant differences in standard length weight relationships by sex, which indicated that a shared model for both genders is appropriate, and isometric growth was detected. Based on the proportion of mature and partially matures fish, the main reproductive period was April through June; size at first maturity was 18.9 cm. Water temperature was not significantly related to the percentage of mature and partially matures Sinaloa cichlids or spawning. These findings provide information for regulating the Cichlasoma beani fishery in this region such minimum legal size and non-fishing period.

Age and growth of sailfish Istiophorus platypterus (Shaw in Shaw and Nodder, 1792) from Mazatlan, Sinaloa, Mexico

Age and growth of the sailfish Istiophorus platypterus were determined for the area off Mazatlan coast, Sinaloa, in the Gulf of California, between September 2002 and August 2003. The lower jaw-fork length and total weight of 572 specimens were measured, and the fourth dorsal spine was collected to determine age. The monthly variation of the sample size displayed a well-defined seasonal pattern, which peaked during the warm period (May–November) and declined during the rest of the year (temperate period). Significant differences were detected in the size structure by sex during the temperate period, with females displaying larger sizes and greater abundance (Female:Male = 3.35:1). In the warm period the size structure was similar, with the sex ratio reaching F:M = 0.73:1. This suggests a different sex-related recruitment in the fishing zone, with males moving more actively than females. While female size remained relatively unchanged over the year, male size increased during the warm period. Age was estimated using the number of growth rings on the cross-sectioned fourth dorsal spine, after the number of absorbed growth rings in the vascularized zone had been estimated. Nine age groups were identified; group-5 was the most abundant, representing 31% of the catch. The trend of the monthly change in the percentage of opaque-edge spines and the average of the marginal increase rate indicated that the formation of growth rings displayed an annual pattern. The von Bertalanffy growth model was adequately fitted to age and back-calculated length data. Significant differences were detected when growth was compared between sexes; females grew faster than males.

Reproduction and community structure of fish from winter catch sites from industrial shrimp bycatch from the northeast and southeast Mexican Pacific

The shrimp fishery is one of the most important fisheries in the world, although the low selectivity from trawling nets has led to the capture of a large number of non-target species. Shrimp-bycatch species include a large number of fish and invertebrate species, of which fish species are the most abundant. The present study aims to determine the community structure as well as the average sizes at first maturity of the fish species from shrimp-bycatch caught from industrial fisheries in the Mexican Pacific from Sinaloa to Guerrero, from January to March 2015. The shrimp-bycatch fish diversity value was found to be 2.22. A total of 37 species of finfish were found, of which five were considered rare. The fish species with the highest Importance Value Index (IVI) levels were Pseudupeneus grandisquamis, Paralichthys woolmani, Lutjanus peru and Diapterus peruvianus. The average size at first maturity was calculated for all species. Of the analysed organisms, 90% were in the juvenile stage, including species with riverine and artisanal fisheries. The present study demonstrates the risk within marine populations to different non-target species due to the poor selectivity of shrimp trawls.

Complete mitochondrial genome of Cominate sea catfish Occidentarius platypogon (Siluriformes: Ariidae)

Abstract The mitochondrion genome of Occidentarius platypogon was assembled from Illumina short reads, and consisted of 16,714 base pairs, with 13 protein-coding, two ribosomal RNAs (rRNAs), and 22 transfer RNA (tRNA) genes. Base composition is 30.7% A, 26.4% T, 28.5% C, and 14.4% G, and 42.9% GC content. Two start codon (ATG and GTG) and seven stop codon (TAA, ACT, CCT, TTA, CAT, AAT, and TAG) patterns were found in protein-coding genes. Control region presented the highest A + T (64%) and lowest G + C content (35.7%) among all mitochondrial regions.

Complete mitochondrial genome of the Chihuil sea catfish Bagre panamensis (Siluriformes: Ariidae)

Abstract The chihuil sea catfish (Bagre panamensis) is endemic of the Eastern Pacific and is a species of fishery importance in the Mexican Pacific. The complete mitochondrial genome of Bagre panamensis has been assembled from Illumina sequencing data. The circular genome was 16,714 bp in lengh, and consist of 13 protein-coding, two ribosomal RNAs (rRNAs), and 22 transfer RNA (tRNA) genes. Base composition is 30.8% A, 26.6% T, 28.2% C, and 14.4% G, and 42.6% GC content. Protein-coding genes present two start codon (ATG and GTG) and eight stop codon (TAA, TCT, CCT, TTA, CAT, AAT, ATT, and TAG). The control region possesses the highest A + T (64.4%) and lowest G + C content (35.6%) among all mitochondrial regions. These data would contribute to the evolutionary studies of related taxa.

Desarrollo Gonádico de Peprilus medius (Peters, 1869) (Perciformes: Stromateidae) del Sureste del Golfo de California, México

The gonadal development assessment is a fundamental work in researching the reproduction of Peprilus medius , on the way to understand its population dynamics and to achieve a sustainable management of its fisheries. The diagnosis based on morphochromatic features is the quicker, more practical and cheaper method, and properly validated, it may be an accurate proce d e. This is particularly useful in researches when it is required to provide prompt and accurate information to support decision-ma king for fisheries management, and during long-term fisheries monitoring to detect changes in reproductive patterns due to environmental an malies. These are issues of concern in P. medius and other fishery resources. In this context, a scale that describes the gonadal development through morphochromatic and histological features is presented, and plus anatomical observations of the reproductive organs. Ov arian development was characterized through six phases: immature, development (sub-phases: early and late), mature, spawning (sub-pha ses: partial and partial post-spawning), post-spawning and resting. Testicular development was described through five phases: immatu r , development, ejaculation, ejaculated and resting. The position and shape of the reproductive organs are apparently defined by t he shape of the fish and the visceral cavity. P. medius’ s gonads show a gonadal lobe at lower position and an upper lobe in the visceral cavity, and both lobes presented a horizontal placement from gonopore toward the back of the fish. In addition, gonadal deformities occurre nce due to deformities in the visceral cavity was evidenced. We recommend to use presented descriptions as a guide in gonadal assessmen t.