Seahorses | Cambodian Diving

Seahorse Surveys

Seahorses face significant challenges in the wild, including habitat degradation and overexploitation, and their ability to cope with additional stress from rapid climate change remains uncertain. Unlike most fish species, seahorses' poor swimming abilities, coupled with the ecological and biological constraints of their unique lifestyle, place heavy reliance on their physiological capacity to adapt to changing environmental conditions. Future ocean changes, particularly ocean acidification, may pose further threats to seahorse conservation, making these captivating creatures important symbols for global climate change awareness.

In Cambodia, particularly around the Koh Rong Archipelago, we have identified nine species of seahorses, highlighting the region's importance for seahorse biodiversity. The International Union for Conservation of Nature (IUCN) recognizes 44 species of seahorses, all of which are either endangered or lack sufficient data for assessment. Conservation Cambodia plays a crucial role in seahorse conservation efforts by contributing our seahorse observations to an international database, aiding in the monitoring and protection of these vulnerable species.

In Cambodia, particularly in the vicinity of the Koh Rong Archipelago, we've had the privilege of identifying nine distinct species of these captivating and charismatic animals.

Seahorses pictured above (not our own photos)

Tiger Tail Seahorse (Hippocampus comes)
- Identified by its double cheek spines, prominent nose spine, blunt spikes on its body, a low coronet, small head relative to its body size and of course its striped tail.
Barbour’s Seahorse (Hippocampus barbouri)
- Identified by its two pairs of cheek spines, a prominent nose spine, stripes on its snout and a spine in front of its coronet
The spiny Seahorse (Hippocampus histrix)
- Identified by its long snout, a single cheek spine, sharp spines on its coronet, a prominent nose spine and sharp body spines.
Winged seahorse (Hippocampus alatus)
- Identified by paired flattened spines behind the head that point outward, sometimes with skin flaps (resembling wings) and thy have no nose spine.
Hedgehog Seahorse (Hippocampus spinosissimus)
- Identified by a low or absent nose spine single or double cheek spines blunter and shorter body spines
Three-Spot Seahorse (Hippocampus trimaculatus)
- Identified by it hook like cheek spine, hook like eye spine, and tree dark spots along the back of its body.
Common Seahorse (Hippocampus kuda)
- Identified by a deep fat body, a low round coronet, and its spines are more like rounded bumps.
Kellogg’s Seahorse (Hippocampus kelloggi)
- Identified by its distinct coronet, thin body, thick trunk rings, and a long backward pointing cheek spine.
Japanese seahorse (Hippocampus mohnikei)
- Identified by a small body maximum 8cm, very short snout compared to its head, ronded double cheek spines.

More About Seahorses

Seahorses are truly fascinating creatures with unique characteristics and behaviors:

Exceptional Eyesight: Seahorses possess excellent eyesight, with their eyes able to move independently on each side of their head. This remarkable feature allows them to simultaneously look forwards and backwards, aiding in their hunt for food, which they typically capture by sight.
Lifelong Pair Bonding: Seahorses form monogamous bonds and often pair for life. Each morning, they engage in an elaborate courtship display to reinforce their bond. This display involves color changes, circling around each other, and spiraling around objects and can last up to an hour.
Territorial Behavior: Females and males each maintain their own territories. Females typically have a larger territory, spanning about 90 square meters, while males have smaller territories of around 0.75 square meters.
Unique Reproductive Role: Seahorses exhibit a rare reproductive strategy where the male carries and nurtures the developing young. After a courtship display, the female transfers her eggs to the male's brood pouch, where he fertilizes them. The number of eggs varies depending on the species, ranging from 50 to 150 for smaller species and up to 1500 for larger species. Gestation typically lasts from 14 days to 4 weeks, during which the young receive nutrients and oxygen directly from the male's pouch.

These remarkable traits and behaviors make seahorses not only fascinating subjects for study but also important indicators of the health of marine ecosystems. Protecting seahorse populations and their habitats is essential for maintaining the biodiversity and resilience of our oceans.

Survey Techniques

The transect method is a systematic approach used to survey and monitor marine biodiversity, particularly in coral reef ecosystems. Here's how it works:

Setup: Two 50-meter transect tapes are carefully laid out on the seabed, positioned parallel to each other and spaced 4 meters apart. Each tape is manned by a two-person team consisting of a scribe and a searcher.
Survey: Each team swims along the length of the transect tape, systematically searching the area two meters to either side. The searchers carefully observe and record the species they encounter, along with additional data such as bottom depth, sex of the individual (if discernible), torso length, snout length, and pregnancy status for certain species.
Data Collection: As the survey progresses, the scribe records the collected data in a standardized format. This includes detailed observations of the species encountered, as well as information about the substrate composition of the seabed.
Analysis: Once the survey is complete, the collected data is compiled and analyzed to assess the abundance, distribution, and diversity of marine life within the surveyed area. This information can provide valuable insights into the health and dynamics of the ecosystem, as well as inform conservation and management efforts.

The transect method is an effective tool for conducting standardized surveys of marine biodiversity, allowing researchers to gather comprehensive data while minimizing disturbance to the habitat.

The Roving Method

The roving method is another valuable approach used in surveying and monitoring marine biodiversity, particularly for species like seahorses. Here's how it works:

Setup: Instead of laying out fixed transect tapes, the roving method involves taking random bearings in various locations. Once a suitable location is identified, a 50-meter transect tape is carefully laid out on the seabed.
Survey: Teams of two, consisting of a scribe and a searcher, then swim the length of the transect tape, systematically searching for and recording the marine life they encounter within a two-meter range on either side of the transect.
Data Collection: As with the transect method, the team records detailed observations of the species encountered, including bottom depth, sex, torso length, snout length, and pregnancy or juvenile status for certain species. This information is recorded by the scribe in a standardized format.
Analysis: After completing the survey, the collected data is compiled and analyzed to assess the diversity, abundance, and distribution of marine life in the surveyed area. This data can provide valuable insights into the local population dynamics and habitat preferences of species like seahorses.

The roving method offers flexibility and adaptability, allowing surveys to be conducted in various locations with suitable habitat for the target species. By monitoring in pairs, researchers can cover a larger area and gather comprehensive data on the presence and characteristics of marine life in the surveyed areas.