Fishing in the Deep Sea

By Luz Erandi Saldaña Ruiz

Popotla is a fishing field located in Rosarito, Baja California, where small boats arrive at the beach with fish and shellfish, but occasionally they arrive with surprises from the depths of the sea: sharks, rays and chimaeras.

You may be wondering what chimaeras are. Chimaeras are closely related to sharks and rays. In Mexico there is a great diversity of fish, and one of the most interesting groups is the chondrichthyans or cartilaginous fishes, whose main characteristic is that they have cartilage skeletons, a similar material to that of our nose and ears. Within this group we find sharks, rays and chimaeras.

It is likely that you have not heard about chimaeras, since they usually live at depths from 300 to 1,000 feet, and it is a challenge to observe and study them in their natural habitat. Therefore, chimaeras have little diffusion and media coverage compared to other shark species. In these depths we also find the prickly shark (Echinorhinus cookei), another species little known and studied.

In Mexico, cartilaginous fishing is a very important economic activity, source of food, income and jobs. The Mexican Pacific Northwest is the main fishing region for this type of fish nationwide, since more than half (62%) of the national fisheries come from this region. Despite the importance of this activity, there is a lack of basic data such as captured species, biological information and how many individuals are caught. Due to this, it is not possible to assess the health status of most species, including deep-sea species that are occasionally caught, such as chimaeras and prickly sharks.

As a biologist I work on many projects related to cartilaginous fishes in the areas of biology, ecology, fisheries, historical reconstruction of catches and conservation. However, I have focused on studying deep-sea cartilaginous fishes and their interaction with fisheries mainly because we know very little about these species, such as the prickly shark and chimaeras, including the impact of fishing. In addition to that, there is a lack of knowledge about these species by the general public.

At the end of 2018, I developed a research project to study deep-sea fish. The objective of the project is to describe cartilaginous fishing in Popotla, with emphasis on prickly sharks (Echinorhinus cookei) and chimaeras, to gather information and establish a baseline of the interaction of these two species with fisheries for future management and conservation actions.

It was thanks to the Save our Seas Foundation that my project was funded, and as of March 2019 the project started, and therefore, one of the most exciting stages in my life as a biologist, researcher and as a person.

The Save Our Seas Foundation aims to protect life in the oceans, they focus on cartilaginous fishes. This foundation supports research, conservation and education projects around the world, and my project was one of those selected for the March 2019-March 2020 cycle.

In this project we have the scientific advice of Oscar Sosa Nishizaki, Ph.D. from the Laboratory of Fisheries Ecology of the Center for Scientific Research and Higher Education of Ensenada (CICESE), who allows his students to support sampling and gives us access to laboratory facilities for sample analysis.

In previous years, prickly shark and chimaeras have been registered in Popotla, even on some occasions, the CICESE Fisheries Ecology Laboratory collected specimens of this type of fish. In addition, the proximity of Popotla to the city where I live, Ensenada, allows us to easily sample. Finally, Popotla provided an excellent opportunity to obtain information on cartilaginous fishes, as well as other caught species.

To achieve the objective of this project, a group of volunteers and I are visiting Popotla and recording the catches in search of cartilaginous fishes, with emphasis on the prickly shark and chimaeras.

Armed with our measuring tape, scale and record sheets, we obtain information related to the biology of the species, size, weight and identify whether it is female or male. We also collect information on what species are being captured, how many individuals are caught, where and how they are caught.

The good relationship and communication with fishers has been very useful to achieve data collection. When we explain and involve them in the project they are very friendly and helpful.

The project is still in process, we are conducting the last field sampling. And during these sampling we have learned a lot about the fishing dynamics of Popotla and its relationship with the catch of cartilaginous species. We are about to start with the final stage of the project in which we will carry out the analysis of all the information collected. I am already eager to tell you the full story of this project soon.

Learn more about this project at

https://saveourseas.com/project/ catch-up-mexicos-shark-fisheries/

♦ LUZ ERANDI SALDAÑA RUIZ has a PhD in Marine Ecology from the Center for Scientific Research and Higher Education in Ensenada, Baja California. She is currently a postdoctoral researcher at the same center.

• Cartamil, D., Santana-Morales, O., Escobedo-Olvera, M., Kacev, D., Castillo-Geniz, L., Graham, J. B., Rubin, R.D., Sosa-Nishizaki, O. (2011). The artisanal elasmobranch fishery of the Pacific coast of Baja California, Mexico. Fisheries Research, 108(2-3), 393-403.

• Comisión Nacional de Acuacultura y Pesca (CONAPESCA). (2017). Anuario Estadístico de Acuacultura y Pesca 2017. Comisión Nacional de Acuacultura y Pesca, Mazatlán.

• Del Moral-Flores, L. F., Morrone, J. J., Alcocer, J., Ponce de León, G. (2016). Diversidad y afinidades biogeográficas de los tiburones, rayas y quimeras (Chondrichthyes: Elasmobranchii, Holocephali) de México. Revista de Biología Tropical, 64(4), 1469-1486.

• Ebert, D. (2003). Sharks, rays, and chimaeras of California (No. 71). Univ of California Press.