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🌊 Marine Data Deficient 🌡️ Temperate

Simushir skate

Arctoraja sexoculata Misawa, Orlov, Orlova, Gordeev & Ishihara, 2020
Max Length
35.2 cm
Max Weight
-
Lifespan
-
Trophic Level
3.7
Depth
-
Climate
Temperate
Resilience
Medium
Vulnerability
38.00/100
Typical Length
-
Depth Zone
demersal

📖 Overview

Simushir skate (Arctoraja sexoculata) is a ray-finned fish. It inhabits marine (saltwater) waters in benthic environments. This species can reach a maximum total length of 35.2 cm. With a trophic level of 3.7, it is a mid-level predator. It is assessed as Data Deficient on the IUCN Red List.

Scientific Name
Arctoraja sexoculata
Authority
Misawa, Orlov, Orlova, Gordeev & Ishihara, 2020
Habitat
Marine
Climate
Temperate
IUCN Status
DD
Max Length
35.2 cm
Trophic Level
3.7
Resilience
Medium
Vulnerability
38.00/100
Salinity
30–40 ppt

🔬 Taxonomy

Genus
Arctoraja
Arctoraja
Species
Simushir skate
Arctoraja sexoculata

🐟 Physical Description

This medium-sized species (ca. max. size 80.0 cm TL, 55.0 cm DW) is distinguished by the following set of characters: dorsal ground color is reddish-brown or greenish-brown, with three pairs of white blotches on disc located beside eyes, and on shoulders and posterior half of disc; lateral margin of tail with 4 or 5 pairs of white blotches located at the tail origin, midpoint, D1 origin, and on inter-dorsal space; ventral surface is almost entirely white; dark blotch around cloaca, dark bands along mid ventral line of tail; dorsal surface of disc with a single scapular thorn, 3-4 nuchal thorns; tail with 20-24 regularly arranged thorns; the median row of thorns discontinuous, no mid-dorsal thorns; orbital thornlets along medial rim of orbit; dorsal surface of disc and tail with fine prickles; prickle band on mid-disc extending along sides of tail; prickles on pectoral fin base relatively sparse; ventral surface is uniformly smooth; disc width 63.1-65.6% TL, length 50.6-53.5% TL; anterior projection (snout to maximum width) 29.7-32.2% TL; head length (dorsal aspect) 18.9-20.6% TL; snout broad and moderately short, preoral length 11.1-14.1% TL, supported by slender, flexible unsegmented cartilage; snout angle 103-119º; eyes rather large with eye diameter 0.22-0.24 times head length, 1.00-1.11 times between orbits; tail relatively long (but shorter than disc width), length 51.5-54.1% TL and 0.79-0.86 times DW, width at first dorsal fin origin 3..8-4.2% tail length; predorsal caudal vertebrae 86-93 .Cross section: flattened.

🌀 Behaviour

Behavioural data for Simushir skate is currently being reviewed.

🦐 Diet

aquatic invertebrates
small fish
algae
detritus

🥚 Reproduction

🐣 Oviparous 📦 Batch Spawner
Spawning Season
spring-summer
Spawn Location
Pelagic
Fertilization
External

🌍 Habitat & Distribution

Marine; demersal; depth range ? - 150 m . Temperate Northwest Pacific: Simushir Island, Kuril Islands.

🌿 Ecology

Zone Preferences
🌊 Marine ⬇️ Benthic
Trophic Level
3.7±0.6

📐 Morphometrics

Length–Weight Relationship: W = 0.00562 × L3.11 (TL)
Max TL
35.2cm

🌡️ Water Parameters & Tolerance

Salinity Range
30–40ppt

🛡️ Conservation Assessment

IUCN Category
Data Deficient
Assessment Date
2021

📊 Population Risk & Fisheries

Population Resilience
Medium
Minimum doubling time
Fishing Vulnerability
38.00/100
Moderate vulnerability
Trophic Level
3.7
Predator
Climate Zone
Temperate
Described By
Misawa, Orlov, Orlova, Gordeev & Ishihara, 2020

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