#28: Many People Ask - Annual Census

How many fish are in the Giant Ocean Tank? How many sharks? Sea turtles? Stingrays? How many different species are in there? Visitors are always curious to know what they are looking at in the exhibit...

In order to find out, we spend the entire month of December counting each and every fish in the tank. Each staff diver picks a species to concentrate on during a particular dive and tallies their numbers. We keep an on-going record up on the dive office door:

We perform the annual census for different reasons. It allows us to accurately answer our visitor's questions. It's also an important part of record keeping and allows us to monitor, and manage, our collection. Because we have data going back four decades, we can track the longevity of particular species. It is also a requirement for AZA institutions like the New England Aquarium.

Some counts are easy, like the three sand tiger sharks. This is our largest female:

Here's a video of all three (You'll see the smallest one has a superficial mark on its tail):

Two loggerhead sea turtles:

We have two southern stingrays:

And a movie of them too:

One nurse shark:

We use underwater slates to write down note:

We use different techniques for different fish. The angelfish love to eat lettuce so it makes them easier to count:

It takes several divers to get an estimate for some of the schooling fish, like these smallmouth grunts:

We have two cownose rays (one thinks its feeding time):

Some of our fishes include four sargassum triggerfish:

Two scrawled cowfish:

Four balloonfish:

We have three green morays, one spotted moray, and one goldentail moray:

In all, we counted 620 individual fish and 129 different species.

Of course, there's only one Myrtle:

- Sarah



  1. Great post! I love all the videos :)

    620 individuals is a lot... do they all eat every day?

  2. Did Don take the videos for you?

  3. Actually, Sarah took these herself!
    I love the cownose ray shots.


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