Gulf of California

How many sharks, chimaeras, skates, and rays inhabit Mexico?

Worldwide, Mexico is well-known for a lot of things: its cuisine, tequila, mariachis, pyramids, and beaches, as well as being the country with the most Spanish-speaking residents (more than 120 million people).

In contrast, however, little is known for the country’s chondrichthyan fauna: a class of fishes containing the sharks, chimaeras, rays, and skates.

To fill the gap in the knowledge of the Mexican marine fauna, scientists from the Instituto Politécnico Nacional – Centro Interdisciplinario de Ciencias Marinas (IPN-CICIMAR) conducted a multidisciplinary study on the extant species of the country’s Economic Exclusive Zone (EEZ) and, as a result, reported a total of 217 extant chondrichthyan species. Their findings are published in the open access journal ZooKeys.

In their updated taxonomic list, the team of Dr. José De La Cruz-Agüero, Dr. Jorge Guillermo Chollet-Villalpando, and Venezuelan graduate students Lorem González-González and Nicolás R. Ehemann report eight chimaeras, 111 sharks and 98 ray and skate species. These numbers equate to 18% of the world’s chondrichthyans.

Split between the Mexican coasts there are 92 species recorded from the Mexican Pacific and the Gulf of California, whereas 94 fishes are identified for the Gulf of Mexico and the Caribbean Sea. Additionally, 31 species are known from both coasts.

“The species richness will undoubtedly continue to increase, due to the current investigations in progress, as well as the exploration of deep-water fishing areas in the EEZ,” comment the scientists.

Considered to be primitive fishes, sharks, skates, chimaeras, and rays are believed to have been inhabiting the planet for the last 420-450 million years. To put it in perspective, the earliest evidence of our species – Homo sapiens – is pretty ‘young’ at 315,000 years.

Not only do these species are peculiar with their lack of a bony skeleton when compared to the more recently evolved fishes, but they also have an unusual digestive system, featuring a spiral valve, where the lower intestine is twisted like a corkscrew to increase the surface area. They don’t have a swimming bladder either. Further, there are about 650 extant species, whereas the known bony fishes are estimated to be over 35,000.

Most of the chondrichthyans are considered either ‘Critically Endangered’ (a classification a step below ‘Extinct’) or ‘Endangered’, according to the Red List of the International Union for Conservation of Nature (IUCN). The majority are also featured in the Convention on International Trade in Endangered Species.

As if to make matters worse, these fishes are also particularly susceptible to overfishing and have a low rate of growth and fecundity (females give birth to between 1 and 25 pups a year).

Original source:

Ehemann NR, González-González LV, Chollet-Villalpando JG, Cruz-Agüero JDL (2018) Updated checklist of the extant Chondrichthyes within the Exclusive Economic Zone of Mexico. ZooKeys 774: 17-39. https://doi.org/10.3897/zookeys.774.25028

Dig it! Two new shrimp species found in burrows at the bottom of the Gulf of California

Although the Santa María-La Reforma lagoon complex in the Gulf of California is one of the most important areas for shrimp fishery, little is known about the crustacean species that live in the burrows dug in the bottom.

In addition to presenting two species new to science, researchers Drs. José Salgado-Barragán, Universidad Nacional Autónoma de México, Manuel Ayón-Parente and Pilar Zamora-Tavares, both affiliated with Universidad de Guadalajara, México collaborated to build on the knowledge of small shrimp species living there. The study is published in the open access journal ZooKeys.

Over the span of about two years – between 2013 and 2015, the scientists conducted series of surveys of the bottom-dwelling crustaceans in Bahía Santa María-La Reforma lagoon, located in the southwest Gulf of California. Following a thorough examination of the collected specimens, they recorded five shrimp species of three genera, inhabiting burrows dug into either mud, sand, or sandy-mud. Two of these species turned out to be previously unknown.

One of the new species is named Alpheus margaritae after Dr. Margarita Hermoso-Salazar, a caridean shrimp expert who helped the authors with the identification of the species. This new crustacean lives in the intertidal zone, where it hides in soft mud and gravel of shells and rocks. So far, it is known exclusively from the coastal lagoon Bahía Santa María-La Reforma, Sinaloa, Mexico. Among its characteristic traits are creamy-white colouration splashed with sparse olive green to light brown patches.

The second new species, Leptalpheus melendezensis, is reported to live in the fine sand of the beach. It is named after the Melendez island – the only locality the species has been identified from. Unlike the rest seven members of its genus (Leptalpheus), its major cheliped lacks adhesive disks.

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Original source:

Salgado-Barragán J, Ayón-Parente M, Zamora-Tavares P (2017) New records and description of two new species of carideans shrimps from Bahía Santa María-La Reforma lagoon, Gulf of California, Mexico (Crustacea, Caridea, Alpheidae and Processidae). ZooKeys 671: 131-153. https://doi.org/10.3897/zookeys.671.9081

How to catch a small squid? First records for the Gulf of California and southwest Mexico

Often avoiding sampling gear with their capability to detect movements and swim their way out of the nets fast enough, the small squids living in the open-ocean zone have so long gone under-researched. The present study, conducted by Dr. Michel Hendrickx, Universidad Nacional Autonoma de Mexico, and his team, seems to provide new and first distributional records of five such species for the Gulf of California and in southwestern Mexico. It also significantly expands the currently known southernmost limit of localities of some of these squids in the eastern Pacific. The research is available in the open-access journal ZooKeys.

The researched five squid species belong to two genera, Abraliopsis and Pterygioteuthis, which although abundant and diverse, have long been shrouded by taxonomic and distributional controversies. To solve them, the researchers used specimens, collected over the span of thirteen years, comprising eight cruises across 113 locations in the Gulf of California and off the southwestern coast of Mexico.

As a result, the scientists concluded a significantly wider distributional range of the species they found. For instance, squids of the Abraliopsis genus were surprisingly found in water deeper than 600 m during the day.

The studied small squids are of high ecological value due to their vital position in the food web. Members of Abraliopsis are important preys for many fishes and mammals, such as the peruvian hake, the Indo-Pacific sailfish, the common dolphinfish and the local sharks. Meanwhile, the representatives of the other researched genus, Pterygioteuthis, are often consumed by larger cephalopods, sea-birds and fur seals. However, their abundance is strongly dependent on temperature, especially when there are fast and significant changes.

The scientists suggest that additional samplings with more adequate equipment, like faster large-sized mid-water trawls, could further bridge the knowledge gaps about these elusive marine inhabitants.

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Original source:

Hendrickx ME, Urbano B, Zamorano P (2015) Distribution of pelagic squids Abraliopsis Joubin, 1896 (Enoploteuthidae) and Pterygioteuthis P. Fischer, 1896 (Pyroteuthidae) (Cephalopoda, Decapodiformes, Oegopsida) in the Mexican Pacific. ZooKeys 537: 51-64. doi: 10.3897/zookeys.537.6023.