Estuarine pipefish (Syngnathus watermeyeri)

Also known as: River pipefish
GenusSyngnathus (1)
SizeLength: up to 13 cm (2)

Classified as Critically Endangered (CR - B1+2abd) on the IUCN Red List 2002 (1)

This slender, cylindrical fish was believed to be extinct in the early 1990s until a miraculous rediscovery in 1995 (6), but the population remains teetering on the very brink of extinction. The long, cylindrical body is a characteristic pipefish shape (5). It is a greenish brown colour and there are dark lines visible on the head and paler lines along the body (2).

Previously found within the Bushmans, Kariega and Kasuka River estuaries in eastern South Africa (4), this species was declared extinct in 1994 (3). An additional population was discovered the following year however, in the East Kleinemonde Estuary, on the Sunshine Coast of South Africa (6).

The river pipefish is a bottom-dwelling fish that inhabits brackish waters (2), and is strongly associated with Ruppia cirrhosa beds (a submerged plant) in the upper and middle reaches of the river (6).

Very little is known about the natural ecology of this species. It is likely that the developing young are carried in some form of brood pouch, following external fertilisation (2). In other members of the genus, the eggs are almost completely enveloped by the folds of the brood pouch, which meet or nearly meet in the middle, and it is likely that this is also the case for this species (7). Pipefish lack teeth and feed by sucking small fish fry and invertebrates into their mouths (2).

The loss of this species from the majority of its former range has been attributed to altered river systems caused by the construction of upstream dams. These developments restrict the supply of fresh water that brings with it essential nutrients required by the phytoplankton upon which the food chain depends (4). Much excitement greeted the discovery of an additional population of this pipefish in the East Kleinemonde Estuary, but these fish are under increasing threat, and not least because they are the last remaining members of the species (3). Developments along the river have led to silting problems; the creation of artificial beaches and the removal of reed beds have further threatened the delicate estuary ecosystem (3).

With the discovery of the remnant population of this species in 1996, the Western District Council adopted a management plan to protect this rare pipefish (3). Measures included a public awareness programme and the discouragement of powerboat riding. Unfortunately, the plan has been poorly enforced and illegal developments, along with an increase in planned developments, have proliferated in the area (3). Unless stricter measures are bought into effect quickly, it is likely that the river pipefish will become extinct once more, this time with no reprieve.

Authenticated (22/10/02) by Sarah Foster. Research Biologist, Project Seahorse.

  1. IUCN Red List (December, 2009)