Sådan identificerer du Twaite Shad

For at identificere Twaite Shad (Alosa fallax) skal du se på disse nøglekendetegn.

Fysiske karakteristika

Kropsform

compressed

Farvetegning

Silvery flanks, darker blue-green to greyish back, and a white belly. Often exhibits a series of 1 to 10 (typically 3-7) distinct dark spots along the upper flank, posterior to the operculum. The first spot is usually the most prominent.

Skæltype

cycloid

Mundens placering

terminal

Kendetegn

Large, deciduous cycloid scales, Deeply forked caudal fin, A series of dark spots along the flank (typically 3-7, but can be up to 10), Absence of teeth on the vomer, Relatively large eye, Strongly keeled belly with scutes

Rygfinne

Single, short-based dorsal fin located mid-body, typically with 16-19 soft rays.

Halefinne

Deeply forked caudal fin, symmetrical lobes.

Brystfinne

Relatively small, low-set pectoral fins, typically with 13-16 soft rays.

Karakteristiske finner

Pelvic fins are abdominal, small, and located beneath the dorsal fin origin. Anal fin is relatively long, with 19-23 soft rays.

Identifikationstips

1. 1

   Spots on Flank

   Count the number of distinct dark spots along the upper flank, posterior to the operculum. Twaite Shad typically have 3-7 spots, whereas the closely related Allis Shad (Alosa alosa) usually has only one, or occasionally two or three, which are often less distinct.

2. 2

   Gill Rakers

   Examine the gill rakers on the first gill arch. Twaite Shad have fewer (typically 40-60) and shorter gill rakers compared to Allis Shad (typically 90-130), which are longer and more numerous, adapted for filter feeding on smaller plankton.

3. 3

   Mouth and Teeth

   Twaite Shad have a more pointed snout and a slightly more terminal mouth. While both species lack vomerine teeth, the overall mouth structure can be subtly different.

4. 4

   Size

   Twaite Shad generally reach a maximum length of about 50-60 cm (20-24 inches) and a weight of 1-2 kg (2-4 lbs), while Allis Shad can grow slightly larger, up to 70 cm (28 inches).

Udforsk Twaite Shad