FAO Species Identification Guide for Fishery Purposes Western

Loliginidae 765
Habitat, biology, and fisheries: Demersal or semipelagic inhabitants of coastal and continental shelf areas
to a maximum depth of about 400 m. Several species are restricted to extremely shallow waters and some
of these penetrate into brackish waters (Loliolus). Typically, they undertake diel movements, aggregating
near the bottom during the day, but dispersing into the water column at night. Many species are positively
phototactic, and hence often are captured with fishing techniques using light attraction. Some species
undergo seasonal onshore-offshore migrations in response to temperature changes. The eggs (which
range from about 2 mm diameter in Photololigo to about 10 mm diameter in Sepioteuthis) are encapsulated
in gelatinous, finger-like strings and attached in clusters to various substrates. Hatchlings resemble the
adults. Recent studies of growth using direct measurements from statoliths reveal that some tropical
loliginids may live only for a few months. Inshore squids are predators on crustaceans and small fishes.
Loliginids are the dominant component of the Western Central Pacific cephalopod catch, but separate
statistics on total catches are not reported for this family. They are a significant component of major trawl
fisheries in the Gulf of Thailand and South China Sea areas; they also are taken as bycatch in many
nearshore trawl fisheries for crustaceans and demersal finfish. Numerous artisanal and subsistance
fisheries take inshore squids either in multispecies catches or as prime target species; gear used includes
purse seines, dip nets, lift nets, cast nets, encircling nets including fixed or tunnel nets in intertidal areas,
baited and unbaited jigs sometimes trolled rather than used vertically, often used at night in association
with light attraction. Loliginids are highly valued for human consumption. They are marketed either fresh,
frozen, dried or processed into cleaned mantles (whole hoods, rings). Small squid are also used as bait
for both commercial and recreational fisheries.
Remarks: A recent study using modern biochemical genetic techniques has highlighted the incomplete
state of knowledge of the taxonomy of the Indo-West Pacific loliginids. This is especially true for members
of the genus Photololigo which includes the majority of the large commercially important species. The
present set of diagnostic morphological characters (fin shape, sucker dentition, hectocotylus structure)
does not always ensure a reliable identification of species. They do not take into account variability with
growth and sex in some of these characters, particularly when these have been poorly and inadequately
defined in the type descriptions (many from the mid 1800s). In many cases, type reference material is
poorly preserved and had poor geographic locality information (e.g. Yokohama market for Loligo edulis,
“Australian Seas (?S.E.)” for Loligo etheridgei. Generic level revisions have recently been undertaken for
Sepioteuthis, Loliolus, and “Loligo”. However, additional studies at the species level over broad geographic
areas are required to clarify the “species complexes” represented by what are currently known as
“Photololigo edulis”, “P. chinensis“ and ”Sepioteuthis lessoniana“. Several poorly known and new unnamed
species are referred to in the literature and ”seasonal forms" with different life history characteristics and of
questionable taxonomic status and distribution are known (e.g. Sepioteuthis lessoniana around Okinawa). This
poor state of taxonomic knowledge has been highlighted previously in workshops and published papers but
little progress has been made.Current and future fisheries assessments of the loliginid resource and subsequent
decisions concerning the management of the stocks are dependent on accurate identification of species.
Therefore, there is an urgent need for a substantial cooperative
region-wide taxonomic study of the genus Photololigo
using classical morphology supported by modern techniques
including allozyme electrophoresis and DNA analysis.
Similar families occurring in the area
Sepiidae (cuttlefishes): the loliginid genus Sepioteuthis
shows some external similarities to cuttlefish but can be
easily distinguished from them by the presence of a gladius
in the dorsal mantle rather than a chalky cuttlebone with a
posterior calcareous spine; the presence of the midline connection
of the fin lobes posteriorly in Sepioteuthis and the
possession of contractile rather than retractile tentacles only
without pockets.
Identification note
The key and descriptions provided below are based on the
existing, inadequate adult character sets and users should
recognize that in some cases, they may not readily assist
with identifying the animals at hand. It should also be noted
calcareous
spine
Sepiidae Loliginidae (Sepioteuthis)
that in some cases, known or suspected species complexes are referred to rather than single species
(“Photololigo chinensis”, “Photololigo edulis” and “Sepioteuthis lessoniana“). Some nominal species
described in the literature and listed below are not included in the key because detailed descriptions have
yet to be published, they remain poorly characterized from the type descriptions or are described from limited
material and their status as valid species remains questionable. These include: