Jack Silverside

Overview

The jack silverside, widely known as the jacksmelt, is a common schooling fish native to the coastal waters of the eastern Pacific Ocean. Although it shares the name smelt, it is actually a member of the New World silverside family and represents the largest species within that group. These fish are an integral part of nearshore marine ecosystems, supporting various predators and coastal fisheries.

Distribution & habitat

This species inhabits the coastal eastern Pacific, ranging from Oregon in the United States down to Baja California Sur in Mexico. They are frequently encountered in shallow inshore environments, including protected bays, harbors, and near piers, often cruising over sandy substrates or around the surf zone.

Appearance

Jack silversides feature an elongated, streamlined body shape typical of pelagic schooling fishes. Their coloration is adapted for open-water life, helping them blend into coastal marine environments.

Biology & behavior

These fish are active during the day and typically form large schools to navigate coastal waters. They exhibit a pelagic lifestyle and can live up to eleven years.

Feeding

As active daytime foragers, jack silversides feed primarily on small crustaceans and algae found throughout their shallow coastal habitats.

Reproduction

Spawning occurs in nearshore marine areas where females release large masses of sticky eggs multiple times per year. These eggs feature specialized adhesive filaments that anchor them securely to shallow-water seaweeds and other substrates, where they are subsequently fertilized by males. Following hatching, the resulting larvae lead a planktonic existence near the water's surface.