Corresponding author: Omar Hernando Avila-Poveda (
Academic editor:
The marine mollusc, commonly called sea cockroach or chiton
Facultad de Ciencias del Mar (FACIMAR), Universidad Autonoma de Sinaloa (UAS), Mazatlan, Sinaloa, Mexico.
Specimen collection was done under a research permit (PPF/DGOPA-130/15) granted to O.H. Avila-Poveda by SAGARPA (currently Secretaria de Agriculturay Desarrollo Rural ‘SADER’) through Comision Nacional de Acuacultura y Pesca ‘CONAPESCA’.
Collection, relaxation and fixation were under specifications of scientific collection activities of wild fauna species (NOM-126-ECOL-2000) and the ethical recommendations for animal welfare, as established under Mexican Law (NOM-033-ZOO-1995) for euthaniing and killing the chitons in a humane way (
Chitons (Polyplacophora) are marine molluscs that mostly inhabit rocky intertidal shores. Chitons have been harvested and used since ancient times as subsistence food by native peoples from coastal areas (
Studies of local artisanal resources are scarce and seldom considered as a potential commercial fishery. Several marine invertebrates present artisanal exploitation, but are now considered possible fishing targets. The number of such species is rapidly expanding globally, partly as a consequence of declining fin-fish fisheries (
Changes in human behaviour and the exploitation of coastal organisms (
Some of the largest species of chiton that inhabit the Pacific coasts of America, shown an unusual behaviour towards the commercial harvest, as they are evolving as small-scale commercial fishery, such as the “Lengua de Perro or Cucaracha de mar”
Although, in the Mexican waters (Pacific and Atlantic), respectively, there are thirty-eight species (
Landing estimates of chiton meat (the foot mass) represent 1 tonne per year (approximately 700,000 chitons) with an estimated value of 35,000 US dollars (
Since chiton fishing is gaining economic importance as a fishing resource, it is necessary to recognise and incorporate it into the National Fisheries Chart. The exploitation might have significant consequences on the population dynamics of the target species
The overall objective of the chiton project is to generate the necessary information of the mollusc Polyplacophora
The general (fundamental) objective was split into eight specific themes and an additional one was raised that covers some aspects of the basic life history of
Reproduction is an essential aspect of the life history of any organism since it is crucial for the perpetuation of the species. For the fishing and aquaculture sector, it is essential to know in depth the reproductive aspect of species of commercial interest, to establish fishing and closed seasons, in addition to farming strategies. Under this premise, the anatomy of the gonad, the early stage of life (sub-juvenile, juvenile, sub-adult), and different reproductive traits such as reproductive season, reproductive cycle, size of sexual maturity, sex proportion, will be estimated according to ecological and latitudinal context.
At present, we will process the gonads by histological methods
Previous supporting studies:
Abadia-Chanona QY,
Abadia-Chanona QY,
Abadia-Chanona QY,
There is a Master thesis ready and some publications in process. The most important conclusion is that the intensity of the reproductive season of
Alvarez-Garcia IL (
Despite previous advances, according to the government, to establish some protection measure, it is necessary to evaluate the life-history traits (reproductive, growth) of the species for its entire distribution area and the differences and similitude along with its distribution range. Only then, can management measures be established and determine if they should be regional or local, which allows the government to make fisheries management decisions, based on the reproductive and growth aspects of the chiton in their geographical distribution.
Therefore, with these advances, we have to study the behaviour along the distribution range to be able to make comparisons across the seven locations.
One of the greatest unknowns in this group of molluscs is the type of food they eat, which has resulted in the fact that most of the Polyplacophorans are considered generically as herbivores. Recent studies have shown that there are up to six types of diets (omnivorous, carnivorous, xylophagous, detritivorous, herbivores, spongivorous) within this taxon (
The basis for evaluating the food items and the differences amongst the seven locations comes from a publication and a conference regarding indices, including a feeding condition index:
Ramirez-Santana BP, Rodriguez-Dominguez G,
There is a Master thesis ready and some publications in process. The most important conclusion is that
Ramirez-Santana BP (
The body shape of animals or the set of observable characteristics of an individual sometimes has variations that are difficult to observe with the naked eye. These variations are the result from the interaction of its genotype with the environment, due to the influence of the environment or physiological processes such as growth and reproduction. In order to compare variations in body shape of the chitons among the seven locations of its distribution, detailed photographs of whole specimen and dis-articulated chiton scleritome have been taken of dorsal and ventral views with a guide (10 mm), maintaining the same apertures and focal distances, following the fundamentals of photography for geometric morphometric analysis (
One of the main aspects of the life history of any organism is its growth and longevity. To know these aspects of Chiton articulatus, there are direct and indirect methods that must validate each other. Here we used Schnute models, where, in the absence of age data; the size structure (length measure) and individual growth of a population are modeled as a function of time. However, this type of analysis requires validation by directs methods as growth by growth lines and in situ growth measurements (marking-recapture). Therefore, sections will be made in the shell plates to observe growth lines; the growth rate will be estimated, and longevity will be calculated. Furthermore, in the field, chitons will be marked and measured periodically to see the difference in growth over time in their natural environment.
There is an advance paper published from a chiton population at the local level:
This advance by indirect methods gives us an estimated 4-5 years of longevity in a regular climatic environment; therefore, we can compare amongst the seven locations and 13 months to see how the latitude (locality) and the months (time) modulate growth between populations.
Using the measurement of the weight of each organ and the comparison between them, we can indirectly understand the exchange of energy between tissues. Therefore, somatic and reproductive indices of adults of
There is an advance paper published from a chiton population at the local level:
Avila-Poveda OH (
In aquaculture, it is essential to know the yield of meat produced by an organism for its production and marketing. It is also necessary to know which region of the distribution has a higher productivity in terms of meat yield and economic return and in the case of establishing aquaculture sites. Therefore, evaluating the natural meat yield of the chitons will allow us to appreciate which region is more productive and in what period of the year. It will also allow us to evaluate this regarding reproduction. Looking ahead to the fishery, it will also enable contrasting the best fishing season (meat yield) versus the closed season (during reproduction). The Somatic index, particularly foot index or meat yield, will be used.
One advance paper was presented at a congress. It is the basis for evaluating the meat yield, later comparing the seven locations:
Martínez-Díaz P, Pérez-Gónzalez R,
This topic is the counterpart of the phenotype. Over time, the characteristics of the species change due to different intrinsic or extrinsic evolutionary forces.
There is an undergraduate thesis:
Aguilar-Rendón TA (
There is a Master thesis ready and a publication in process.
Alvarez-Cerrillo LR
It was also presented at conferences:
Alvarez-Cerrillo LR, Alvarez-Cerrillo LR,
During this large-scale project to explore the life-history traits of
It allowed us to generate a publication:
Another topic was that, during reproductive activity (gonadal maturity), the gonad increases in volume and exerts internal pressure in three dimensions (length, width and height), which compresses the ventral organs towards the foot and also pushes the collective set of plates (scleritome) dorsally. The pressure changes the scleritome influencing its width and height.
Alvarez-García IL, Abadia-Chanona QY, Rodríguez-Domínguez G,
In addition,
Alvarez-Cerrillo LR,
For the development of the previous objectives, the global methodology and the logistic and operational technical detail are presented.
The facilities, laboratories and some basic equipment of the Faculty of Marine Sciences (FACIMAR), Autonomous University of Sinaloa (UAS), located in Mazatlan, Sinaloa, Mexico, are the headquarters of this project; therefore, in this faculty, the laboratory processes, storage, biometric measurements and dissection of chitons are carried out.
A technical visit was made to each sampling site, the material was delivered and the coordinating researchers were trained on how to collect, fix and conserve organisms, both in the field and in the laboratory. Subsequently, every three months, the samples were sent to FACIMAR-UAS, in Mazatlán.
The chitons were collected simultaneously in the rocky intertidal of seven locations, one per State, throughout the total area of their distribution in the Mexican Pacific (Fig.
The total collection time was one year. A monthly research campaign was conducted from October 2015 to October 2016. FISHING PERMISSION was made available by the government to carry out this research. The collections were monthly and simultaneous in each locality and around the second week of each month (days 7 to 16). To maintain simultaneous sampling, one researcher was supported by the State.
Between 30 and 40 adult chitons of
Under the premise of the previous general objectives (themes), a global methodology was established for the collection of organisms in each of the seven states of distribution of the species, following the ethics and care of the animals. Furthermore,
With the help of volunteers and students of FACIMAR-UAS (Fig.
The development of the project complies with the deadlines established in the work programme.
Despite fulfilling each phase using equipment borrowed from other institutions, it is essential to continue to have the autonomy to use the equipment, agents and materials for better holistic progress in the project.
With some advances of the information generated, a request was made to the CONAPESCA authorities regarding the regulation of the management of fishing resources and requesting the recognition and incorporation of this
Attached is the list of
The project had initial financing of $ 6344 USD from the Faculty of Marine Sciences, General Directorate of Postgraduate and Research, Universidad Autonoma Sinaloa, Mexico. This initial financing allowed sampling in the 7 locations per one year, obtaining around 3000 chitons, as well as the transfer of samples to FACIMAR, and the initial reagents for storage. However, exchange reagents for maintenance and lockers for storage of samples are missing.
Other topics of the project has been funded by myself. A large part of reagents and supplies have been contributed from my own resources.
By another hand, the project has been presented 3 times to CONACYT, and it has seemed fascinating but has never received support because after the fascination it seems to them that it is not an issue that can meet the objectives. However, in 6 years of the project and a single annual sampling in 7 places, I have shown through students and publications that if it can be carried out showing results.
With regard to equipment, I have had support from other institutions; however, sample transfers demand a cost and sometimes an equipment rental. Rental supplied by me.
Thanks to Quetzalli Yasu Abadia-Chanona for the scientific and logistical advice, sampling and training assistant and for acting as the online community manager of the project on social networks. Thanks to researchers and students (Figure 9) who coordinated and supported the collection of chitons in each State every month and for one year, which was relevant to achieve the overall objective of the project.
Mexican Chiton Project
Facultad de Ciencias del Mar (FACIMAR), Universidad Autonoma de Sinaloa (UAS), Mazatlan, Sinaloa, Mexico.
Specimen collection was done under a research permit (PPF/DGOPA-130/15) granted to O.H. Avila-Poveda by SAGARPA (currently Secretaria de Agriculturay Desarrollo Rural ‘SADER’) through Comision Nacional de Acuacultura y Pesca ‘CONAPESCA’.
Collection, relaxation and fixation were under specifications of scientific collection activities of wild fauna species (NOM-126-ECOL-2000) and the ethical recommendations for animal welfare, as established under Mexican Law (NOM-033-ZOO-1995) for euthaniing and killing the chitons in a humane way (
Omar Hernando Avila-Poveda wrote and developed the entire theme, process and methodology of this project.
The project Chiton of the Mexican Tropical Pacific, arises as an activity and research proposal related with the commissioned of Avila-Poveda OH as
The start of the project was financed by the General Directorate of Postgraduate Studies and Research (PROFAPI-2014/023), UAS-FACIMAR, and CATEDRA-CONACYT, Mexico; and it was for the technical visit in each sampling location and delivery of sampling material.
Omar Hernando Avila-Poveda has financed the project himself, also with help of donations (reagents and supplies) from colleagues and collaborators at each sampling site. However, the project currently requires financial and logistical support to continue making efficient use of 100% of each sampled animal.
Specimens of the mollusc
Example of sale and consumption of meat (foot, in colloquial Spanish “Lengua”) of
The food menu of some restaurants in Acapulco, Guerrero, including a dish with chiton, common name "Cucaracha/cockroach".
Image processing and indices of the radula of
Equipment used to take pictures of each chiton and example of some chitons photographed.
Locations of
Group of volunteers and collaborators of the QUITÓN PROJECT in FACIMAR-UAS. The project has a logo registration (brand), which is used on the shirts. Shirts used in the field and presentations (congresses, workshops) are shown.
Schematic diagram of the methodological process through which the chitons will pass to fulfil each of the proposed themes.
Collage (application letters) of the procedure to request the recognition and incorporation of this
List of collaborators in the project.