It’s a well-worn cliché that you can’t manage what you can’t measure. In fishing, that means understanding how many fish are in the sea so we know how many we can sustainably catch.
Under New Zealand’s Quota Management System, assessments of biomass are needed to guide the setting of Annual Catch Entitlements. Good information begets good decisions. And with hundreds of stocks to manage – 642 of them to be precise – there is a lot of scientific assessment to be done to understand what is really going on beneath the waves.
The fishing vessels themselves are vehicles for the data collection needed, as Ben Steele-Mortimer from Seafood New Zealand explains.
“We rely quite heavily on collecting biological information from the vessels about what fish is being caught, how big they are, how old they are and the sexes of different fish. That information is used along with a lot of other information to model and provide estimates of total biomass in our fisheries.”
Right now, this type of work is mostly done by Government observers on the deepwater fishing vessels. Ben is the Environment Programme Manager for the Deepwater part of Seafood New Zealand. He focuses a lot on helping fishers avoid interactions with protected species such as marine mammals and seabirds.
“Prioritising observer placement on vessels is driven by several factors and the focus of a lot of observer coverage is on protected species and compliance. At times the need for fish sampling is put down the priority list. Although the observers obviously do collect a lot of biological data, sometimes it’s not weighted enough in that area for us to have the data needed to support stock assessments.
“So what we’re working on is getting vessels across our hoki fleet to collect biological data, such as length frequency data from the vessels. It’s been several years since we’ve tried to get something like this off the ground. But it’s all been a very paper-based and resource-intensive operation.”
And paper-based has proved to be a very impractical way to do things, as Ben explains.
“Basically, in the past crew were provided with A4 sheets of paper and required to write tallies on how many fish, different sizes, all of that. And then that information is then sent to us [at Seafood New Zealand], where it was manually transcribed into a digital format. But this was a logistically cumbersome process which was ineffective for the long-term.”
However, the information is needed, so a new approach had to be tried.
That’s where Ben and the team gratefully borrowed an idea developed by the rock lobster industry and involved a Nelsonbased tech company called ZebraTech. That tech company has developed “deck loggers” which can be used to log information about every cray or fish caught.
“The crew would use these loggers, measure out fish and plug it into these loggers, and it records it all in a useful way. And then when they get to shore, they can send this
data off via cellular. There’s a quick switch in there that sends it off remotely, and it’s all sent to a central database where it’s stored, able to be analysed and then used for stock assessments in the future.”
Ben says the loggers are easy to use, practical and durable, although some manual labour is still needed – crew have to measure 100 fish from each tow and plug in the measurements. In total, crew across just three vessels have measured over 38,000 fish in only a few months.
The loggers are currently being trialled on a small number of hoki vessels. The trial has been quietly going on for six months and Ben is pleased with the results and feedback so far.
“We’ve had a really good success and good uptake from the crew and operators. And we’re now looking to scale it up to the rest of our hoki fleet. And with that, we’ll also work on a back-end data management system, where we can ensure that the data is robust enough to be used in stock assessments.”
The unit is also useful for management in our fisheries. For example, if a vessel has caught a large number of small fish and is close to a certain threshold, the logger alerts them and triggers a move on protocol.
Ben’s next steps are working on ensuring the robustness of the data, so that everyone inside and outside the fishery can confidently rely on the information collected. He says there are various statistical approaches which can be used to ensure the data is reliable and can be compared against existing observer figures.
Using this logging system could help reduce costs and could increase the volume of useable data we get from across the fishery. Helping ensure we can measure and therefore can manage better.
