Cape Hope Squid
Cape Hope Squid, Chokka squid, Calamari
Loligo reynaudii, commonly called Cape hope squid, is a neritic, nektobenthic species, meaning that it lives in the coastal waters and swims near the bottom of the sea. It is widely distributed over the continental shelf and slope, at depths of 0 to 384 m (136 to 300 m by day); migrate vertically after dark (Jereb et al, 2010). Populations are mainly distributed in the south and west coasts of South Africa (Rosa et al, 2013). Interestingly, those in the west coast occur at greater depths compared to those at the south coast. Also, the west coast populations comprise mostly of immature-maturing subadults. In this instance, subadults refer to individuals that have passed through the juvenile period but not yet attained typical adult characteristics or morphological features. The Cape hope squid is an opportunistic predator feeding on a wide range of prey. Adults feed on polychaetes, crustaceans, cephalopods and teleost fish larvae and juveniles. L. reynaudii is preyed upon by a wide variety of opportunistic predators, including skates, rays and sharks, a large number of teleost fishes, seals, dolphins and seabirds. Males grow larger than females with maximum mantle length of 400 mm and females up to 240 mm (Augustyn, 1990) and (Augustyn, 1991).
Description/How to recognise a Cape hope squid
Loligo reynaudii has an elongated slender body with long fins and mantle. The left ventral arm is used to store and transfer spermatophores to the female, the distal part of its arm is modified and bearing 44 to 68 tiny outgrowths on the surface that are in rows (Guerra et al). Limbs are expanded, with suckers in transverse rows, the median segment of limbs is greatly enlarged, and their horny rings are smooth with 78 mm mantle length. Its eyes are covered with a membrane which is part of the skin covering the head. It has reddish-brown pigment containing light reflecting cells on the head and mantle. When alive, the colour can change from dark red to almost translucent (Jereb et al, 2010).
Lologo reynaudii has a very regular foraging pattern. They forage at early dusk to late night. At times, the foraging pattern can switch to early morning because they are easily attracted by artificial light, particularly on their spawning grounds. Under lights, the majority remain in the shadow with one or two at a time entering the lighted area and catching the prey.
In most studies of L. reynaudii, communications were based on the mating period where lone males contest aggressively for paired females on the spawning grounds. The large lone males intrude on the pairs and engage the paired consort male in an agonistic contest. They use skilful movements usually by jockeying and swimming under the consort male to intrude and positioning themselves near the female and visual body patterns followed by escalation to physical Fin beating. Sometimes the intruder would strive directly under the consort and swim forcibly upwards attempting to lift or displace the consort. The paired consort male would parry the advances of the competing intruder and try to maintain his position immediately adjacent to the female. The winner will be the contestant that would be paired with the female after the contest (Hanlon et al, 2002).
Loligo reynaudii occurs in one of the most diverse and highly variable environments found anywhere in the world mainly between the Orange River, Port Alfred and the Great Fish River, and also in relatively large numbers in Southern Angola where spawning is also known to occur (Guerra, et al). In the oceanography of South Africa’s east coast and outer Agulhas Bank, L. raynaudii is strongly influenced by the warm, fast-flowing Agulhas Current. In South African waters more than two thirds of the adult biomass is concentrated on the south east coast (Roberts and Sauer, 1994).
Cape hope squid lives in the coastal waters and swim at the bottom of the sea. It is widely distributed over the continental shelf and slope at depths of 0 to 384 m (136 to 300 m by day and migrate vertically after dark). The west coast population is found in greater depths than on the south coast, and it consists mainly of immature and maturing subadults. Although the Cape hope squid aggregate in dense spawning shoals, the offshore distribution is more uniform and widespread (Jereb et al, 2010).
Loligo reynaudii is an opportunistic predator taking a wide size range of prey. Adults feed on polychaetes, crustaceans, cephalopods and teleost fish larvae and juveniles. The selection of prey seems to be a function of size and not adulthood or maturity. Cannibalism is generally low offshore, but increases on the spawning grounds. Mature animals mainly feed at night compared to day feeding especially on their spawning grounds. There are also seasonal differences in the diet, where in summer the feeding is higher than in winter (Sauer and Lipiński, 1991).
Sex and life cycle
Mating and egg laying occur gradually throughout the year, but generally concentrated in spring and early summer in warm protected inshore locations. Adults move to spawn in the relatively sheltered embayments (a broad inlet of the sea where the land curves inwards) found on the South Coast (Hanlon et al, 2002). The spawning behaviour is particularly complex, squid move up to 200km between inshore spawning sites, generally in an eastward direction. Females commonly mate with multiple males over short time periods and access to sperm from different males and multiple paternity within the offspring of individual females appears common. The distribution of maturity stages suggests that most hatchlings eventually move away from the spawning grounds to feed over the south and west coast shelf, returning to the south coast spawning grounds as adults where they may or may not spawn immediately (Roberts and Sauer, 1994).
THE BIG PICTURE
Friends and foes
Loligo reynaudii is preyed upon by a wide variety of opportunistic predators, including skates, rays and sharks, a large number of teleost fishes, seals, dolphins and seabirds (Roberts and Sauer, 1994). Fisheries are the worse enemy due to their harvesting for commercials. They target the spawning aggregations throughout the day and the night, using lights to increase fishing efficiency. Nematodes (parasites) from the family Anisakidae and Cestodes have been observed frequently in the mantle tissue and inside of the stomach wall (Sauer, 1995).
There are no known special features or strategies for Loligo reynaudii. However, species under the same class (Cephalopoda) generally have a unique nervous system and sensory organs. The development of these organs in Cephalopods is much greater than those of their counterparts (e.g. Gastropods). This enables them to use their brain more effectively – exhibiting a higher level of intelligence. Also, Cephalopods have multiple chemical sensory organs that enable them to have advanced vision. It is for this reason that these organisms have been used as research models in physiology, aging, molecular biology, neuroscience and immunology to understand similar phenomenon in humans for various medical reasons relating to disease diagnoses and treatment (Guerra et al).
Poorer world without me
The Cape hope squid is the most important commercially harvested cephalopod in South Africa. Its fisheries has the highest variability in both biomass and catches with annual catches varying from 2 000 to 13 000 tons (Sauer, 1995). L. reynaudii is sometimes harvested as a bycatch (unwanted marine creatures that are caught in the nets while fishing for another species) in the commercial inshore nets catch fishery and handline lure fishery (Augustyn, 1990).
People and I
South African Loligo valguris reynaudii is used to bait more traditional commercial fish and also for human consumption (Fries, 2010). Its fisheries are commercially profitable with relatively small initial input costs in terms of vessels and equipment. Export of frozen squid from handline lure fishery has been a valuable source of foreign exchange to South Africa (O'dor, 1998).
Conservation status and what the future holds
Cape hope squid conservation status has been assessed by biomass-based stock assessment model and results were expressed in terms of the number of person-days permitted in the fishery (DAFF, 2014). The current reviewed results indicated a decline in the biomass and limited resources in the production of the squid in comparison to the previous years (DAFF, 2014), which can have devastating economic consequences to the fishing industry during years of reduced production. It was therefore, recommended that the current fishing pressure should be reduced as it was heavily fished in 2014.
The species is similar to its European and West African relative L. vulgaris, the two taxa (formerly called L. reynaudii and L. vulgaris) being nominally separate species. However, morphological and biochemical studies show that physical and genetic differences between the two taxa were small and that their gene pools are probably isolated from each other by an oceanographic barrier of Namibia. Loligo vulgaris reynaudii occurs from southern Namibia to approximately East London on South Africa's east coast (Augustyn, 1992).
Augustyn, C.J., 1990. Biological studies on the chokker squid Loligo vulgaris reynaudii (Cephalopoda; Myopsida) on spawning grounds off the south-east coast of South Africa. South African Journal of Marine Science, 9(1), pp.11-26.
Augustyn, C.J., 1991. The biomass and ecology of chokka squid Loligo vulgaris reynaudii off the west coast of South Africa. South African Journal of Zoology, 26(4), pp.164-181.
Augustyn, C.J., Llpiński, M.R. and Sauer, W.H.H., 1992. Can the Loligo squid fishery be managed effectively? A synthesis of research on Loligo vulgaris reynaudii. South African Journal of Marine Science, 12(1), pp.903-918.
Department of Agriculture, Forestry and Fisheries. 2014. Status of stocks Report, available from http://www.nda.agric.za/doaDev/sideMenu/fisheries/03_areasofwork/pdf .
Fries, A.S., 2010. A gap analysis of the distributions of cephalopod species worldwide with a focus on commercially important species.
Guerra, A., Gonzalez, A.F., Roeleveld, M. and Jereb, P., CEPHA LO PODS.
Hanlon, R.T., Smale, M.J. and Sauer, W.H., 2002. The mating system of the squid Loligo vulgaris reynaudii (Cephalopoda, Mollusca) off South Africa: fighting, guarding, sneaking, mating and egg laying behavior. Bulletin of Marine Science, 71(1), pp.331-345.
Jereb, P., Roper, C.F.E. and Vecchione, M., 2010. FAO Species Catalogue for Fishery Purposes No. 4. Vol. 2. Cephalopods of the World. An Annotated and Illustrated Catalogue of Cephalopod Species Known to Date. FAO Fish. Synop, 3, p.277pp.
Lipinski, M.R., Hampton, I., Sauer, W.H.H. and Augustyn, C.J., 1998. Daily net emigration from a spawning concentration of chokka squid (Loligo vulgaris reynaudii d'Orbigny, 1845) in Kromme Bay, South Africa. ICES Journal of Marine Science: Journal du Conseil, 55(2), pp.258-270.
O'dor, R.K., 1998. Can understanding squid life-history strategies and recruitment improve management?. South African Journal of Marine Science, 20(1), pp.193-206.
Roberts, M.J. and Sauer, W.H.H., 1994. Environment: the key to understanding the South African chokka squid (Loligo vulgaris reynaudii) life cycle and fishery?. Antarctic Science, 6(02), pp.249-258.
Rosa, R., Pierce, G.J. and O'Dor, R.K., 2013. Advances in Squid Biology, Ecology and Fisheries. Nova Biomedical.
Sauer, W.H.H., Goschen, W.S. and Koorts, A.S., 1991. A preliminary investigation of the effect of sea temperature fluctuations and wind direction on catches of chokka squid Loligo vulgaris reynaudii off the Eastern Cape, South Africa. South African Journal of Marine Science, 11(1), pp.467-473.
Sauer, W.H.H. and Lipiński, M.R., 1991. Food of squid Loligo vulgaris reynaudii (Cephalopoda: Loliginidae) on their spawning grounds off the Eastern Cape, South Africa. South African journal of marine science, 10(1), pp.193-201.
Sauer, W.H.H., 1995. The impact of fishing on chokka squid Loligo vulgaris reynaudii concentrations on inshore spawning grounds in the South-Eastern Cape, South Africa. South African Journal of Marine Science, 16(1), pp.185-193.
Name: Mpho Mmethi
Organization /Cost Centre: SANBI Marine Programme
Date: 23 November 2016
Phone number: 076 467 8361
Species: Loligo reynaudii d’Orbigny, 1841