There has been a “massive spike” in the number of injured and sick sea turtles in need of care in southeast Queensland, according to turtle experts.

Sea World vets on the Gold Coast have already seen a record 80 turtles enter their facility this year.

Turtle rehabilitation coordinator Siobhan Houlihan said the number was already “25 to 30 turtles higher than last year.”

The previous record for one year was in 2014, when 71 turtles were treated at the center.

To the north, the Australia Zoo has received 79 turtles from the Gold Coast, Redlands, Moreton Bay and Sunshine Coast regions – by far the highest number in recent years.

Many turtles introduced to Sea World suffered from “floating syndrome”, which could be caused by multiple factors, including parasites and poor water quality.

Ms Houlihan said that despite this inherent lack of information, turtles were affected by “a lot of things that are caused by humans.”

Other ailments included collisions with boats and entanglement or ingestion of fishing lines.

In the case of turtles found floating after collisions with boats, veterinarian Claire Madden said it was impossible to say what happened first.

“Are they sick initially and then they float? Therefore, they are more likely to be affected because they are already floating,” she said.

Weather impacts on the welfare of turtles

Weather conditions are also likely to have played a role.

Ian Bell, conservation officer at Queensland Parks and Wildlife, said that type of rise “is really closely related to the El Niño Southern Oscillation Index and can have a positive or negative effect.”

Dr Bell said under strong El Niño conditions there was less precipitation and more sunlight penetrating into the seawater, excellent conditions for seagrass growth.

“About a year after a strong El Niño episode, we are seeing a very high nesting season because there are a lot of beautiful, fat adult females who are ready to go and lay eggs,” Dr Bell said.

“On the other hand, if we have a high incidence of La Niña… we see a lot of precipitation, a lot of runoff, very cloudy waters and the penetration of sunlight is low, so the sea grass is not going. so good.”

While the importance of the Great Barrier Reef as a turtle breeding and nesting site is well known, Moreton Bay’s role as a feeding ground is attracting less attention.

Six of the seven species of sea turtles that inhabit Australian waters are found in the bay’s seaweed-rich environment between breeding seasons in the waters of the Great Barrier Reef.

Dr Bell said the effect sediment could have on this crucial food source was “a bit like throwing a tarp over your lawn.”

“Usually we get this really cloudy water after these heavy rains and then we drain the land through rivers and streams and eventually into bays and along the coast,” he said.

When sea grasses were malnourished, so could turtles, especially younger animals with less body fat to survive the winter.

“There is more pollution in the bay”

Whenamooka Aboriginal Lands and Seas Management Agency director Darren Burns said the impact of sediment on water quality was visible.

“I’ve been on the island my whole life – I can see the dirty brown water that was once confined to the South Bay Islands – that dirty brown water rises all the way to Peel Island these days.” , did he declare. .

Mr Burns said “there are significant changes and alterations in the people” of the region.

“Without statistics and precise figures, it would be very difficult to pinpoint the sediment as the main cause,” he said.

“But you can take a step back and go back to population growth – there are more people, there are more ships, there is more pollution in the bay.”

Mr Burns said there was evidence of elevated pollutant concentrations following similar mapping to sediments in the bay.

While there is data showing that turtles that feed in coastal areas have much higher levels of toxicity than their open water counterparts, Dr Bell said the effect these pollutants may have on turtles was not clear.

“We certainly have a much better idea of ​​the impact of pollutant levels on humans and mammals – but on reptiles, we don’t know,” he said.

More humans means more problems for turtles

The constant and prolonged growth of the human population in the Southeast is of concern to those implicated in turtles in the region.

“The denser our population, the more likely we are to have problems with wildlife and humans,” Dr. Madden said.

Queensland was the only state to experience significant growth in fiscal year 2020-21.

During the same period, more than 33,000 new construction applications were approved for the Gold Coast, Greater Brisbane and Sunshine Coast regions.

Mr Burns said the growing population of people using the marine park could negatively influence the bay’s marine life, including turtles.

“It’s got a lot of people in the water these days – Moreton Bay is just a limited area,” he said.

“It’s inevitable – there are turtle strikes, there are dugong strikes, whale strikes – and it goes hand in hand with population growth.”

Despite what many see as clear anecdotal evidence that the bay was busier than ever, the number of boats registered in the area has only increased gradually.

Mr Burns said many were not respecting the designated slowdown zones that were in place to protect wildlife.

Collisions with boats are cause for concern, but Dr Madden said recreational fishing and the widespread use of crab traps in the area poses a greater threat to the turtle population.

“Too often these pots are turned off for days – they should be turned off in the evening and checked in the first light in the morning – that just doesn’t happen,” she said.

“The fact that we were pulling crab traps out of Pumicestone Passage with the skeletal remains of a turtle gives you an indication of how long that crab trap had been there.”

Green turtle count bounces off “zero baseline”

Dr Bell said he was optimistic, especially for the Moreton Bay green turtle stock, whose population has rebounded from a “zero baseline” after being decimated by the soup industry. turtles from the 1920s and 1930s.

“The genetic stock of green turtles south of the Great Barrier Reef is increasing [and] for 40 years, ”he said.

Dr. Madden doesn’t expect people to stop enjoying the Moreton Bay area.

“At the end of the day, it’s such a beautiful place and people are enjoying it,” she said.

“There are options to have sustainable, biodegradable hooks and fishing line, for example, or have a different motivation to check their crab pots more frequently.”