Software calculates the reproductive potential of fish

The Instituto de Investigaciones Marinas de Vigo has led the development of a software that enables the automatic calculation of fish reproductive potential. The software is called “Govocitos” and is distributed free of charge. It may improve the projections of fish stocks and their preservation.

Reproductive potential differs among species and individuals. A female of Ocean fish (Mola mola) may lay fifty million eggs per year. Meanwhile, a four-spot megrim female (Lepidorhombus boscii) could lay around seven hundred thousand. Pictured, Ocean fish (Barcelona’s Aquarium).Every year, in some cases every two years, the European Commission proposes the total allowable catch (TAC) figures for fishing operators and commercial species. These figures are established according to the projections made by experts, which includes the prevision of different fish populations, and whether the populations are stable or declining. To do so, experts assess factors like the proportion between catches, the amount of mature fish and juvenile.

Nevertheless, a factor which is not always taken into account is the reproductive potential of fish (capacity of having a viable offspring), because requires a tedious and difficult analysis.

Francisco Saborido, head of the Fishery Ecology department at the Instituto de Investigaciones Marinas of the CSIC explains that the reproductive potential differs among species and individuals. “Bigger females are more fertile than smaller ones; for instance, a female of Ocean fish  (Mola mola) may lay fifty million eggs per year.  Meanwhile, a four-spot megrim female (Lepidorhombus boscii) could lay around seven hundred thousand”. Differences can happen also among different populations of a single species. “For instance, anchovy in the Cantabric sea can have more reproductive potential than its equal in Mediterranean Sea”, adds Saborido. Differences can happen also among years, although not so dramatically.

In any case, reproductive potential is a factor that could be included to make the projections, but it requires analyzing ovarian tissue of some of the caught individuals. The technique, called stereology, requires a manual examination and counting the oocytes in a single image of the ovary (a cross section). The area covered by mature oocytes is calculated, and the result extrapolated in order to obtain an estimation of the number of oocytes in the whole ovary. Due the complexity of the process, this technique is not applied in fisheries as a general rule.

“Sometimes, estimations are roughly done using a grid with hexagonal cells whose area is known, therefore the area occupied by mature oocytes can be estimated approximately. Actually, until now, counting all pixels occupied by the oocytes in a histological section is virtually impossible”, adds Rosario Dominguez, scientists at the Instituto de Investigaciones Marinas. There are some commercial devices that make the task faster, but they can cost thousands of euros.

The software is distributed free of charge and it is twice as fast to make the analysis.

Now, a team led by the CSIC’s Instituto de Investigaciones Marinas de Vigo, has developed a software that enables to make this analysis automatically and easily. Scientists from the universities of Vigo and Santiago de Compostela have been also involved in the project.

The software, which is called “Govocitos”, is distributed free of charge and it is twice as fast to make the analysis. Rosario Dominguez, coordinator of DETEPRE project, funded by the local government Xunta de Galicia, says that “the technique is based on the automatic detection and classification of oocytes from an ovarian tissue image, using algorithms that assess texture, colour, size and form of oocytes. These characteristics change progressively as the cell develops”.

Once this analysis is done, the software automatically makes all the mathematical calculations to extrapolate the result, in order to obtain the fertility, besides all the measurements of every single cell analysis. The results can be exported to a spreadsheet or a database connected to the software.

Screen of the software Govocitos. Until now, the scientists have applied Govocitos to a few species (pouting, hake, Lane Snapper, and myctophidae), with 80% effectiveness, but it can be applied to any specie as Govocitos includes a training module. It is only required a person with expertise to assess the ovarian tissue of the specie, to classify the oocytes images and to introduce these data once in the software.

Using Govocites will help also scientific research. “Hake is one of the puzzles we try to solve, as we don’t know how long is the laying season, nor how many times the female lay eggs. Hake fertility is undetermined and there is not synchronicity among the different populations, therefore its reproductive potential cannot be accurately estimated”, says Rosario Dominguez.

This new software can be useful for biologists or fishery and aquaculture  professionals. Other sectors can find useful the program, like medicine or engineering. “Stereology is a technique often used in medicine and mining. The technique is aimed at calculating the number or volume occupied by some particles inside of something, no matter if these particles inside something are tumors inside an organ, mineral veins inside a rock or  pores inside a ceramic structure”, adds this expert.

Several institutions and scientists have shown interest in this software. The scientists, working at the CSIC and at the University of Vigo and at University of Santiago de Compostela, expect that “Govocitos” will be widely accepted.

“As the use of the software progressively increases, new improvements will arise to be introduced in the software. Govocitos has been created with enough flexibility to make that possible. Nevertheless”, says Dominguez, “the lack of funding could be a handicap to develop all the potential of the software”.


Video de Govocitos: