'Small' fish make the big time

A leading international science magazine has recently featured the research of a team led by Museum scientist Jeff Leis on how tiny larval fishes survive and find a reef home in the big blue ocean.

One of the things I love about my job is that I get to learn amazing stuff all the time. This week, I put up a display highlighting the work of Jeff Leis and his team on larval fishes. Although the display can't feature too much information, I thought I'd take the time to read all the materiaI I was given, and have a browse though the website (I have to admit I didn't really know much beyond the fact that larval fish are babies, and that we have lots in our collection). I got a little carried away, but it was worth it. Not only did I discover some really interesting facts about these tiny baby fishes but also, if you want to know anything about them, Jeff is just about the best person in the world to ask.

Some of the things I found interesting were:

• larval (baby) fish rarely look like adults and are really hard to identify
• squirrelfish larvae are the fastest and have been clocked at doing around 65cm per second - not bad for something only a centimetre long!
• larval fish are caught in a light trap and then released individually and followed for 10 minutes. The ‘follower’ has to be extremely vigilant as some of the fish are only a millimetre long

More about Jeff's research on larval fishes

Nearly all fishes living on coral reefs have a larval stage that lives a few weeks to months in open water away from the reefs. These larvae differ from their adult stage in appearance, habitat and diet. They also face enormous obstacles to survival – growing from a few millimetres to a few centimetres, and developing physically and behaviourally. All this makes it challenging to study them, but understanding their ecology and behaviour is vital for the fishes and for fisheries.

During the time in open waters, the tiny larvae are subject to dispersal by currents. The geographic scale over which larvae disperse is the natural scale of their populations, hence the scale over which fisheries must be managed. Marine parks also need to know this in order to be efficiently designed and managed.

Nearly every aspect of larval-fish behaviour so far examined has produced surprising evidence – and revolutionised our view – of the sophistication and range of their abilities. Although it’s now clear that fish larvae behaviour plays a critical role in their dispersal, the biological processes involved in dispersal remain largely hidden. Jeff and his team have recently been awarded a 3-year ARC Discovery grant to study how dispersing larvae determine the direction they swim, how this varies spatially and what sensory cues they use.