Pacific bearded brotula

Brotula clarkae is a fish of the order Ophidiiformes that lives in the tropical eastern Pacific from the Gulf of California to Peru ^[1]. Hubbs described it in 1944, and the World Register of Marine Species keeps it as an accepted species ^[2]. In Peru it is known as congrio rosado and is among the species in artisanal landings ^[3].

It is a species of growing fishery interest. Females mature at about 62 cm total length in the Colombian Pacific, where they spawn in successive pulses between May and October ^[3],[3], and in Costa Rica a size at maturity of about 72 cm was estimated for both sexes combined ^[4]. The IUCN Red List classifies it as Data Deficient ^[5].

FAO describes the genus Brotula as having the body completely covered with small, overlapping cycloid scales, barbels on the snout (6) and on the chin (6), 8 branchiostegal rays, and pelvic fins of 2 rays each inserted at the level of the preopercle, well behind the eye ^[1]. In the family, the dorsal, caudal and anal fins are confluent and the dorsal begins before the anal ^[1].

The fish studied in Colombia measured between 17.5 and 107.5 cm total length ^[3], and in Costa Rica males reached 92.8 cm and females 93.0 cm, with mature adults of 67.2 to 98.4 cm ^[4].

Similar species

• Brotula ordwayi: Brotula ordwayi also lives off Peru and the Galapagos, where FAO records it as locally abundant, whereas it says Brotula clarkae is caught only occasionally; the same catalogue, from 1999, admits that a key to separate the species of the genus was not possible ^[1],[1].

It is endemic to the tropical eastern Pacific and has been recorded from Palos Verdes, California, to Paita, Peru ^[4]. Adults live on soft mud bottoms and juveniles in epipelagic waters, and a depth range of 40 to 650 m is cited ^[4].

In northern Peru, the fish on whose gills two new parasites were described came from Puerto Pizarro, in the Tumbes region ^[6]. In Colombia the species was taken by demersal trawl and bottom longline in the industrial fishery and by espinel in the artisanal one, within the region called Ensenada de Panamá ^[3]. In Costa Rica, seasonal reproductive aggregations were observed in shallow waters, where it is commercially exploited ^[4].

In the Colombian Pacific, 754 individuals were examined between 1994 and 1996: 354 males and 400 females, a sex ratio statistically equal to 1:1 ^[3],[3]. The size at which 50 % of females begin to mature was 61.3 cm total length by the graphic method and 62.3 cm by the statistical method ^[3].

Spawning is batch-wise: high gonadosomatic indices indicate a prolonged maturation period with several pulses between May and October, and between 3.1 and 4.5 batches of hydrated oocytes were estimated per reproductive period ^[3]. In seven females analysed, mean fecundity per batch of hydrated oocytes was 1,005,657, with individual values from 455,100 to 1,305,000 ^[3].

In Costa Rica, with 348 fish collected between 2011 and 2012, size at maturity was 71.9 cm total length for both sexes combined, with an interval of 68.5 to 74.5 cm, and the 87 % of the 302 immature individuals dominated the sample ^[4]. The authors read the difference from Colombia as a possible sign of a still recent exploitation in Costa Rica, and warn that a single figure should not be extended to the whole range of the species ^[4],[4].

Juveniles feed on shrimps and crabs, while the adult diet is composed mainly of bony fishes and stomatopods, besides echinoderms and molluscs, according to the synthesis of earlier work given by the authors of the Costa Rican study ^[4].

In the Colombian Pacific, the spawning period coincides with the transition between the dry and the rainy season, which the authors think may be tied to the food supply ^[3]. During reproduction the sex ratio shifts slightly, which the authors attribute possibly to a spatial segregation of the sexes, with females somewhat more abundant below 70 cm and males from 80 cm ^[3].

On the gills of fish from Puerto Pizarro, in northern Peru, two new species of monogeneans were described, Brotulella laurafernandae and Brotulella luisahelenae, which form a new genus ^[6].

The current IUCN Red List assessment classifies it globally as Data Deficient ^[5]. A 2016 study notes that little is known about its biology and life history, and that work on its reproduction was limited to Colombia and Ecuador ^[4].

For the Colombian fishery, the authors recommended keeping the mean catch size above 62.3 cm and establishing closed seasons that protect the reproductive period, in May and June or in September and October ^[3]. The Costa Rican authors call for study of its aggregations, essential habitats and spawning seasons before sustainable levels of exploitation are set ^[4].

In Peru, artisanal landings of congrio rosado totalled 54 tonnes in the first half of the year 2000, according to an IMARPE statistical report cited by the Colombian authors ^[3]. In 1999, FAO listed it as a species caught only occasionally ^[1].

In the Colombian Pacific, 9,924.48 tonnes of white fish were landed between 1994 and 1996, of which 9.34 % was merluza, the local name for this genus; artisanal fishing supplied 65 % and industrial fishing 35 %, and the species ranked among the ten of greatest commercial importance in the area ^[3]. In Costa Rica it became a target of trawling and artisanal fishers after populations of deep-water shrimp declined ^[4].

In the available literature on Peru, the species appears mainly tied to fishing: it is among the artisanal landings of the first half of 2000 ^[3], and a study published in 2023 describes parasites of fish from Puerto Pizarro, in the Tumbes region in the north of the country ^[6]. The sources consulted report no diving observations; according to one of them, adults live on mud bottoms at 40 to 650 m depth ^[4].