Constellationfish

Silvery in color during the day, darker at night. Branchiostegal rays: 9-10 (Ref. 35838). Unique arrangements of the photophores on the tail, five separated groups containing 2-4 light organs (Ref. 37473).

Annual species probably spawning year round (Ref. 4739). Spawns more than once with egg batches about 100-360 eggs/ovary pair, the number increasing with animal size (Ref. 4739).

Dorsal spines (total): 0; Dorsal soft rays (total): 7 - 10; Analspines: 0; Analsoft rays: 22 - 25

Oceanic and mesopelagic, with marked stratification of size with depth. Generally non-migrant or only short diel vertical migrations. A selective daytime feeder on copepods (mainly Pleuromamma and ostracods, Conchoecia). Consume primarily copepods (Ref. 51328).

Oceanic and mesopelagic, with marked stratification of size with depth (Ref. 4739). Generally non-migrant or only short diel vertical migrations (Ref. 4739). A selective daytime feeder on copepods (mainly Pleuromamma and ostracods, Conchoecia) (Ref. 4739). Also Ref. 58302.

Valenciennellus tripunctulatus

Valenciennellus tripunctulatus is known from the Atlantic, Pacific, and Indian oceans and the Mediterranean Sea (Grey, 1964). It is one of seven mesopelagic fishes characterized as widespread in the Atlantic (Backus et al., 1970), where it occurs in all of the zoogeographic regions defined by Backus et al. (1977).

A medium-size sternoptychid, V. tripunctulatus reaches 30 mm SL in our collections. This appears to be the maximum size in most areas, although Hopkins and Baird (1981) took specimens up to 35 mm in the Gulf of Mexico, and Torchio (1960) described a specimen 70–75 mm total length from the Mediterranean. The species was uncommon in the study area, ranking fourth in abundance among sternoptychids in all seasons (Table 5). Of the 380 specimens captured, 230 were taken during the seasonally paired cruises, including 108 in discrete-depth samples, with 78 of these from noncrepuscular tows (Table 4).

DEVELOPMENTAL STAGES.—Sex and/or stage were determined for 306 specimens. Postlarvae were 10–14 mm, juveniles 13–18 mm, subadult males 15–26 mm, subadult females 16–26 mm, adult males 19–28 mm, and adult females 20–30 mm SL. Despite the broad overlap in size ranges between sexes, mean standard lengths are significantly greater (p = <0.01) in females than in males, both among subadults (22.6 mm vs. 19.6 mm) and adults (24.6 mm vs. 22.1 mm). Subadult females have eggs mostly 0.1 mm in diameter, with a few larger eggs, 0.2–0.3 mm, scattered throughout. In adults, almost the entire surface of the ovary is covered with eggs 0.4–0.7 mm. In most subadult males, one testis (usually the left) is longer and thicker than the other; in adults, the testes are equal in length and diameter.

REPRODUCTIVE CYCLE AND SEASONAL ABUNDANCE.—Valenciennellus tripunctulatus appears to spawn in all seasons, with no spawning peak(s) evident. Individuals of both sexes probably spawn at least two or three times and live about one year.

Only two postlarvae (in winter) and no juveniles were taken in noncrepuscular discrete depth tows (Table 18). The total number of postlarvae (17) and juveniles (12) captured during cruises 1–14 represent only 5.6% and 3.9%, respectively, of all specimens. Hopkins and Baird (1981) also noted the paucity of small specimens in their samples from the Gulf of Mexico; thus, it appears that these diminutive stages are inadequately sampled by midwater trawling gear. The scarcity of juveniles also may be explained by the protracted metamorphosis of V. tripunctulatus (Ahlstrom, 1974; Badcock, 1977), which results in a relatively lengthy postlarval but short juvenile stage.

Our postlarvae were taken from February through September, with most captures (9) in July. Adults were taken from January through November, and were represented by 10–19 specimens on each cruise made between mid-March and early September. The widespread occurrence of these two life history stages indicates that spawning occurs in all seasons, and the relatively constant abundance of adults (Table 18) suggests little or no seasonal variation in spawning intensity.

Subadults were the most abundant stage in all seasons (Table 18). Their very wide size ranges and the broad overlap with adults (Figure 4) clearly indicate that V. tripunctulatus is a repeat spawner. Since very few adults exceeded the maximum sizes of subadults, the larger “subadults” actually were postspawning adults approaching a second (or third) sexual maturation. Furthermore, there is no real indication of seasonal size variation. In late spring and late summer, when specimens were most numerous, subadult males were 17–25 mm and 15–26 mm, respectively, with mean SL's of 19.9 mm and 19.4 mm. Similarly, subadult females were 18–26 mm in late spring and 16–26 mm in late summer, with mean SL's of 22.4 mm and 22.3 mm, respectively. In view of its small maximum length, V. tripunctulatus probably lives only about one year. We suspect that sexual maturity is attained 6–9 months after hatching, and that individuals spawn at least two or three times.

In the Central Pacific near Hawaii, where it is one of the more abundant stomioids, V. tripunctulatus also spawns year-round (Clarke, 1974). Clarke indicated that mature females were abundant in all seasons and noted that there were no seasonal trends in size composition among his 600 specimens. Hopkins and Baird (1981) also noted little seasonal size variation in collections made from March to October in the Gulf of Mexico. Apparently, V. tripunctulatus spawns in all seasons throughout its geographic range.

SEX RATIOS.—Total numbers of males exceeded total numbers of females in all seasons, but the only significant difference was in late spring, when adult males outnumbered adult females by 2.3:1 (Table 19). When all subadults and adults (including damaged, unmeasureable specimens) from cruises 1–14 are compared, the ratio is 144 males: 133 females, and the difference is not significant from 1:1. We suspect that the slight tendency for males to predominate is explained by differential susceptibility to the collecting gear, with more females (with average size larger than males) than males avoiding the net.

VERTICAL DISTRIBUTION.—Of 78 specimens taken in noncrepuscular discrete-depth tows, 71 (91%) were from depths of 351–550 m both day and night (Table 20), suggesting that V. tripunctulatus is a permanent, nonmigrating resident of these depths at all times. Only two specimens, both subadults, were taken deeper, in a day tow at 651–700 m in late spring. These specimens cannot be dismissed as contaminants, since the preceding tow was from below 1500 m. Only five specimens, two postlarvae and three subadults, were from 301–350 m, our shallowest capture interval. These were night captures, and the presence of subadults at this depth suggests increased susceptibility to capture at night, although the possibility of a very minor upward movement cannot be ruled out. On the other hand, the presence of postlarvae at 301–350 m suggests stage-depth stratification, which is also indicated by the tendency for mean SL's to increase with increasing depth at all times, although the trend is clear only in day catches in late summer, where the number of specimens begins to approach adequacy (Table 20).

Other studies report size-depth stratification and overall depth ranges similar to ours, but there is some indication of area to area differences in diel depth concentrations. Loeb (1979) reported small (7.1–9.9 mm SL) postlarvae from open net tows made at 100–225 m and 100–350 m in the North Pacific central gyre, but none from shallower or deeper tows. In open net sampling near Hawaii, V. tripunctulatus (10–32 mm SL) was taken mostly at 400–550 m by day, and specimens from 525 m were significantly larger than those taken at 500 m (Clarke, 1974). The night depth range was 200–330 m, and Clarke concluded that the species undergoes a small but distinct upward migration. Hopkins and Baird (1981) reported on discrete-depth captures of V. tripunctulatus from two stations in the Gulf of Mexico. At 27°N, 86°W the depth distribution was 250–550 m by day and 180–500 m at night, and the authors concluded that any vertical migration is very limited. In the Loop Current gyre, the species was somewhat deeper (370–550 m) with no day-night difference discernible. Discrete-depth sampling in two areas of the eastern Atlantic also produced somewhat different results. Near the Canary Islands, V. tripunctulatus was found at 350–500 m by day and at 250–450 m at night, indicating a slight upward migration (Badcock, 1970). At 30°N, 23°W, where the species exhibited size-depth stratification at 200–400 m day and night, there was a slight upward shift in the peak frequencies of larger specimens at night, which Badcock and Merrett (1976) attributed to increased vulnerability to capture in darkness.

Valenciennellus tripunctulatus has been shown to feed almost exclusively by day in three different areas: the eastern North Atlantic (Merrett and Roe, 1974), off Hawaii (Clarke, 1978), and the Gulf of Mexico (Hopkins and Baird, 1981). This commonality of behavior suggests that the most parsimonious explanation for the apparent geographic differences in diel depth distributions is net avoidance, the magnitude of which varies with environmental parameters such as water transparency. If vertical migrations occur, they are very minor, and are usually too difficult to detect by ordinary means.

PATCHINESS.—Only two significant CD values were found, one in the daytime (late spring, 351–400 m) and one at night (late summer, 451–500 m). In each case, subadults and adults were involved. This scarcity of clumping agrees with the feeding study of Baird and Hopkins (1981), who concluded that V. tripunctulatus has a sparse, nonaggregated distribution.

NIGHT:DAY CATCH RATIOS.—In late spring, subadults were twice as abundant by day as by night, but adults were equally abundant night and day (Table 21). In late summer, this pattern was reversed, and thus the total abundance differs little from 1:1 in the two seasons. However, when the winter night captures (Table 20) are included, the night:day catch rate for all specimens and all seasons combined is 1.8:1. Furthermore, when all captures (nondiscrete plus discrete) are considered, night captures exceed day captures by 151 to 108, a ratio of 1.4:1. Thus, V. tripunctulatus appears to be more susceptible to capture at night. This is supported by data from two areas of the eastern North Atlantic, where night captures exceeded day captures by 1.6:1 (Badcock, 1970) and 2.6:1 (Badcock and Merrett, 1976).

These night:day catch ratios may be explained by diel differences in behavior. V. tripunctulatus feeds almost exclusively by day, and apparently searches a considerable volume of water to obtain its daily ration (Baird and Hopkins, 1981). Thus, the species is more alert by day and better able to avoid capture. At night, its silvery sides become darkened by the expansion of melanophores, which also obscure the luminescent organs (Badcock, 1969; Krueger, 1972). The resulting loss of reflectivity may serve to reduce the likelihood of detection by bioluminescent predators. This nocturnal camouflage, coupled with the cessation of feeding, suggests that V. tripunctulatus becomes quiescent at night and thus more vulnerable to midwater trawls.

全球性種類，從溫帶到熱帶和地中海皆有其分布。臺灣分布於西南部。

一般以底拖網捕獲，不具食用經濟價值，通常做為下雜魚用。

體延長，甚側扁。頭較短高。吻短而鈍，小於眼徑。眼大而圓，略突出呈筒狀，指向背方。眼間隔窄。口裂近垂直。上頜邊緣為前頜骨與上頜骨所構成。前頜骨邊緣為凹，上頜骨具齒緣下彎呈弧形，末端伸至眶後下方。下頜較長，突出於上頜之前。兩頜齒各1列；前頜骨齒小，上頜骨齒較大，長短不等；下頜齒細小。犁骨、腭骨、翼骨及舌上均未發現有齒。鰓孔大。鰓耙細長。具假鰓。ORB1；OP 3；Br 6，IP 3+4=7；PV 15-18；OV 2+1+1+1=5；VAV 5；AC 3+3+3+2+4=15；D 7-9；P11-13；V 6-7；A 24-25。尾部顯著長於頭與軀幹之和。背鰭短，起點位於體背中部；臀鰭頗長，起於背鰭起點稍前下方；胸鰭長；腹鰭短小，腹位。尾鰭叉狀。

大洋性中層魚類。以橈腳類、端足類、介形蟲、磷蝦和小魚等為食。

Valenciennellus tripunctulatus, commonly called the constellationfish, is a species of fish in the family Sternoptychidae (hatchetfish).

Feeds on copepods

Grand Bank to Gulf of Mexico and further south into South Atlantic

oceanic and mesopelagic, with marked stratification of size with depth

nektonic