Species identification by morphology
A total of 15 species were identified from fish eggs, belonging to 12 families; 12 species were identified from fish larvae, belonging to 12 families. One species, Dinematichthys iluocoeteoides was shared between the fish egg and larva samples. Four egg samples (E009, E017, E018, and E019) could not be identified due to partial damage (i.e., missing the key feature for identification); two larva samples (L011 and L012) were unable to be identified due to the missing key feature for identification.
A morphological analysis apparently revealed 15 species from the fish egg samples, of which 7 were identified using the characters of egg diameter, oil ball, and pigmentation in the egg, and 8 were identified using the features of egg diameter and/or oil ball. Based on our observations, eggs of Pampus argenteus (E020, E021, and E022) are 1.39-1.41mm in diameter with an oil ball of 0.39mm and pigments evenly distributed on the back of embryo and spread to the caudal stalk; there are also pigments inside the oil ball. Eggs of Konosirus punctatus (E011, E012, and E013) are 1.28-1.43mm in diameter with dotted pigments evenly distributed on the back of the embryo.Trichiurus lepturus eggs (E032 and E033) are 1.90-2.00mm in diameter with an oil ball of 0.48mm and a pair of pigments accumulated on the head; there are a pile of pigments on the pectoral fin and the ventral surface of tail. Pseudaesopia japonica eggs (E023, E024, and E025) are 1.84-2.03mm in diameter with the absence of oil ball and many star-shaped pigments on the embryo and yolk. The Scomber japonicus egg (E027) is 1.02-1.38mm in diameter with an egg ball of 0.33mm and two parallel lines of pigments on the back of embryo. TheDinemathichthys iluocoeteoides egg (E010) is 0.80mm in diameter with an oil ball of 0.11mm and a dendritic pigment on the embryo.Larimichthys crocea egg (E014) is 1.70-1.21mm in diameter with some small oil balls nearby a large yellow oil ball of 0.31mm.Scomberomorus niphonius eggs (E028, E029, and E030) are 1.60-1.70mm in diameter with an oil ball of 0.4mm. Acanthopagrus schlegelii egg (E001) is 0.98-1.20mm in diameter with an oil ball of 0.20-0.23mm. Chrysochir aureus eggs (E004 and E005) are 070-0.79mm in diameter with an oil ball of 0.2mm. Coryphaena hippurus eggs (E006, E007, and E008) are 1.35-1.46mm in diameter with an oil ball of 0.26-0.36mm. The Sillago japonica egg (E031) is 0.63-0.70m in diameter with an oil ball of 0.15-0.18mm oil ball. Lateolabrax japonicus eggs (E015 and E016) are 1.26-1.33mm in diameter with no oil ball. Auxis rochei eggs (E002 and E003) are 0.95 mm in diameter with no oil ball. Saurida macrolepis(E026) is 0.90-0.97mm in diameter and has no oil ball.
A morphological analysis revealed 12 species of fish larvae that belong to 12 families. Eleven species were identified by the characters of dorsal fin, anal fin and pigmentation; one species was identified by dorsal fin and anal fin characters. We observed that theChaeturichthys stigmatias larva (L004) has a dorsal fin of VII-22 rays, an anal fin of 19-20 rays, and star-shaped pigments under the chest cavity and above and below the anus; also there is a large black star-shaped pigment at the end of anal fin and buttock.Sebastiscus marmoratus larva (L015) has a dorsal fin of XII-11 rays and an anal fin of III-5 rays; there are dense pigments above the chest cavity and 7-8 star-shaped pigment dots evenly arranged from the anus to the caudal stalk. Larvae of Larimichthys polyactis (L009 and L010) each have a dorsal fin of X-31-36 rays, an anal fin of II-9 rays and one little pigment on the abdomen and another on the buttock below the chest. Chelidonichthys spinosus larva (L005) has a dorsal fin of IX-16 rays, an anal fin of 16 rays, and star-shaped pigments on the head, chest cavity, abdomen, ventral fin and first dorsal fin. Acanthogobius hasta larva (L001) has a dorsal fin of VIII-18 rays, an anal fin of I-16 rays, and a large star-shaped pigment on the base of ventral fin; there are star-shaped pigments above the bladder, above and at the end of digestive tract and on the base of anal fin and the base of caudal fin. Engraulis japonicus larva (L007) has a dorsal fin of 14-16 rays, an anal fin of 15-18 rays, and star-shaped pigments on the head, anterior gill cover and above the digestive tract; there is a little pigmentation in the lower caudal fin.Callionymus enneactis larva (L003) has a dorsal fin of IV-8 rays, an anal fin of 7 rays, and star-shaped pigments arranged in parallel on the back of body, on the midline of body side and from the anus to the caudal stalk as well as a dendritic melanin on the abdomen.Benthosema pterotum larva (L002) has a dorsal fin of 12 rays, an anal fin of 17 rays, and one large chrysanthemum-like pigment in the front of abdominal sac and another at the end of digestive tract. The larva (L006) of D. iluocoeteoides has a dorsal fin of 80 rays, an anal fin of 59 rays, and pigments evenly distributed on the top of fish head, on the gill caps behind the eyes, on the back from the anus of abdomen to the caudal stem, and on the end of body spine. Harpadon nehereus larva (L008) has a dorsal fin of 11-13 rays, an anal fin of 13-15 rays, and seven large melanin plaques in the chest. Salanx ariakensis larvae (L013 and L014) have a dorsal fin of 12 rays, an anal fin of 25-27 rays, and pigments evenly distributed on the upper part of digestive tract and the base of fin membrane of abdomen. Takifugu xanthopterus larva (L016) has a dorsal fin of 16-18 rays, an anal fin of 14-16 rays, and dense pigments at the end of snout, on the back of body, and above and below the chest cavity.