Literature Review On Larval Fish

CHAPTER 2

LITERATURE REVIEW

2.1. The larval fish stages

Fish larvae are part of the fauna that eat smaller organisms. According to Leis and Ewart, (2000) they characterize larval stage to end with the fulfillment of full outside quantitative feature characters, the entry of any mobile structure. For the larval stage according to Termvidchakorn and Hortle, (2013) the larval stage can be divided into three which are yolk sac stage, pre-larval stage and post larval stage; whereas according to Leis and Ewart, (2000) the larval stage is divided into segment that outlined by formation of the caudal fin and flexion on the notochord. Ahlstrom and Ball, (1954) stated that the terminologies of the development stage of larval fish divided into yolk

Identification of fish larvae

Larval fish identification in this study was mainly depended on literature description and book. These guides are the compilation of the obtainable description of larval stages of fish around the world which are a guide to commonly occurring larval stages of fishes in Kenyan Coastal Waters by Mwaluma et al., (2014) and the larvae of Indo-Pacific Coastal fishes: An identification guide to marine fish larvae by Leis and Ewart, (2000).

There are 2 main characteristic used to identify fish larvae which include body and gut shape.

2.2.1. Body shape

Description and the body shape of fish larvae are very useful for identification (Leis and Ewart, 2000). The general shape of body that contains the body depth (BD) to body length (BL) is classified as follows:

Very elongated BD < 10% BL

Elongated BD 10-20% BL

Moderate BD 20-40% BL

Deep BD 40-70% BL

Very deep BD > 70% BL

The data to body shape are relative to the size which during the development body size may become smaller. Some structures become smaller during in the process growing to another stage.

2.2.3.

Costa et al. (2011) studied in fish larva community in an Amazonian estuary. All samples were collected in a 300 µm mesh conical cylindrical plankton net attached to a flow meter (hydro bios) and the net was towed through subsurface water horizontally for 5 minutes at a speed of 1.5 knots. Sample was removed from the net and fixed immediately in 4% formalin.

iv. Ara et al. (2014) collected fish larvae by using bongo nets with mesh size 500 µm, mouth diameter 0.3m and length 1.3m (Figure 2) in daylight. A flow meter (hydro-bios) was attached to the net in order to determine the volume of the water filtered. The bongo net, then towing 30 minute sub-surface from each station. Figure 2: Bongo net (mesh size 500 µm, mouth diameter 0.3m and length 1.3m).

v. Sukumaran et al., (2014) use a cast net measuring 2.5 m long, with a mesh size varying from 7 mm at the base and 15 mm at the apex was employed in the collection of fish throughout the period of study and the net was hauled 10 times during every collection at the sampling site.

vi. Mwaluma (2010) studied community structure and spatio-temporal variability of ichtyoplankton in Kenyan Coastal waters method use the light trap fabrication and deployment. The traps were deployed per tide during high tide at depth 10-18m for 12 hours. Figure 3: The locally fabricated light trap with original (with metal frames)