Sand Sole

The sand sole is a right-eyed flatfish in the family Pleuronectidae, found along the northeastern Pacific coast from Alaska to central California. Despite the common name, it is classified with true flounders rather than true soles. The species is distinguished by several free, unbranched rays at the front of its dorsal fin that extend beyond the fin membrane, a feature uncommon among related Pacific flatfish. Sand sole inhabit shallow, sandy nearshore waters and estuaries, making them one of the more accessible flatfish species for shoreline and shallow-water observation along parts of the Pacific coast.

• Elongated oval body, moderately slender
• Eyes on the right side of the head
• Upper side is light brown to olive with scattered small dark and orange-tinted spots
• Several long, thread-like, free dorsal fin rays extend forward beyond the fin membrane near the head—a key distinguishing feature
• Underside is white
• Adults typically reach 20-40 cm, with large individuals to about 63 cm

The free, filamentous front dorsal rays are the clearest way to distinguish sand sole from similar Pacific species such as starry flounder or English sole, none of which show this feature.

Sand sole are found along the northeastern Pacific coast from the Gulf of Alaska south to central California. They inhabit shallow, sandy nearshore waters, bays, and estuaries, typically at depths from the shoreline down to about 120 meters, though they are most common in shallower water than many other Pacific flatfish. The species favors clean, well-sorted sand bottoms in bays and open coastal areas, and juveniles are frequently found in very shallow estuarine nursery habitat. Adults range somewhat farther offshore than juveniles but generally remain within reach of sandy, current-influenced coastal substrate.

Sand sole are active, relatively fast-swimming flatfish that forage over open sandy bottoms for small fish, shrimp, and other invertebrates, often venturing farther off the bottom than more sedentary flatfish species. They rely on cryptic coloration when resting but can move quickly to pursue prey or evade predators. Spawning occurs in nearshore coastal waters, with females producing pelagic eggs that drift before hatching into free-swimming larvae. Juveniles commonly settle in shallow estuarine and bay habitats, which serve as important nursery grounds, before moving to slightly deeper coastal sand flats as they mature.