Fish migration patterns are hard to nail down regardless of where you study. But it\u2019s even more difficult to do with tropical storm Irene making landfall. <\/p>\n
Just ask Helen Bailey, an associate research professor at the University of Maryland\u2019s Chesapeake Biological Laboratory. She and co-author David Secor, professor at the lab, saw firsthand just how much the movements of striped bass can vary when compared to that of white perch. <\/p>\n
Part of that was due to the fish themselves, but another was partly due to the impacts of two tropical storms (the second was Lee) that crossed right through their study\u2019s Hudson River Estuary location in fall 2011. Still, they obtained results that are useful for management of the fish in the estuary and may also prove critical for safeguarding their stocks in a future where extreme weather systems are predicted to become more common.<\/p>\n
\u201cWe were partly focused on striped bass because my co-author had been attaching acoustic tags to the fish around New York Harbor,\u201d said Bailey. \u201cAnd it just so happened that we were able to study during these storms.\u201d<\/p>\n
Tropical storm Irene came first, followed just a few days later by tropical storm Lee. The effects of these systems was clear, as investigators saw key water quality markers drop.<\/p>\n
U.S. Geological Survey streamgages along the Hudson River revealed a sudden decline of water temperatures. Salinity and dissolved oxygen data, obtained through the Hudson River Environmental Conditions Observing System, also dropped. Scientists also considered measurements of water level and discharge.<\/p>\n
\u201cTemperature plummets, salinity plummets, and they just get washed out,\u201d said Bailey, noting that some striped bass were able to maintain their positions in the river by finding ideal refuge habitat. \u201cBut many fish did move out because the conditions weren\u2019t suitable for them.\u201d<\/p>\n
Investigators say that the fish tend to move south in storms. During the extreme weather, the striped bass largely just moved further to the south, according to acoustic tag data. A few bass went south and then ventured back up, potentially making exploratory runs to see if conditions had improved for overwintering in the estuary. <\/p>\n
But once the second storm hit, those fish that had moved south cleared out.<\/p>\n
\u201cAfter the first event, they moved further down,\u201d said Bailey. \u201cBut after the second storm, they bolted.\u201d<\/p>\n
She says that there was quite a bit of variability between fish response. While some of the striped bass shot south to get away from the tropical storms, others stayed put. <\/p>\n
And there really wasn\u2019t any clear reason as to why certain fish left or remained.<\/p>\n
\u201cIt wasn\u2019t the bigger fish. We had a small range of sizes,\u201d said Bailey. \u201cEven the smaller fish could find refuge.\u201d<\/p>\n
Through some of her previous work in marine science, Bailey has seen how common individual responses can be. From whales to sea turtles, it seems to hold up that creatures don\u2019t all act the same just because they\u2019re members of the same species.<\/p>\n
\u201cWe see that individual variability a lot, so I wasn\u2019t surprised. But I think this is how these animals survive, how they cope and survive,\u201d said Bailey. \u201cWhen we think in terms of what the fish do, we can\u2019t look at them as a whole. Acoustic telemetry has given us more insight into how complex these animal behaviors are.\u201d<\/p>\n
In the traffic-heavy harbor, Bailey says it\u2019s key to make sure that there aren\u2019t impediments to stop striped bass from evacuating when extreme weather hits. Managers can also help to ensure that these fish stocks continue to be diverse.<\/p>\n
\u201cWe have this variability. If we lost that diversity, then those events that they previously survived might have a different outcome,\u201d said Bailey. \u201cAnd that would be catastrophic.\u201d<\/p>\n
In the future, additional research needs to be done. Bailey says more fieldwork, fish tagging and modeling can help to figure out what impacts extreme weather events to come could have. And she\u2019s currently working to better understand the habitat preferences of striped bass so that managers can know when the fish are more or less likely to be in certain areas. <\/p>\n
Full results of the research are published under open-access license in the journal Scientific Reports.<\/p>\n
Top image:\u00a0A researcher holds a striped bass. (Credit: National Oceanic and Atmospheric Administration)<\/span><\/em><\/p>\n","protected":false},"excerpt":{"rendered":" An investigation tracking striped bass in the Hudson River Estuary captured how the fish moved following tropical storms Irene and Lee.<\/p>\n","protected":false},"author":13,"featured_media":26967,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,459,458],"tags":[118,60,109,111,230],"class_list":["post-26971","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-featured-articles","category-fish-science-fish-science","category-fish-science","tag-aquatic-species","tag-featured","tag-news-ticker","tag-tropical-storms","tag-university-of-maryland"],"remote_post_permalink":false,"remote_post_featured_image":false,"yoast_head":"\n