Valter Santos RIP, my friend.

Will Darwall Olaf enters the water! Happy days at Otter Point Lake Malawi - snorkeling to watch the cichlids. Needless to say, not so many cichlids to see after Olaf "dived" in!! V. good memories...

Ryan Wasserman Olaf on a recce trip for my MSc in 2008

Taryn Murray Olaf, still at DIFS, was the lecturer in charge of our Honours class's fieldtrip to Swartvlei back in 2009. He wanted to show us how to cast net so settled on this random little (manky) pool. I think we caught nothing but mud and algae.

Taryn Murray Contrary to this pic (also from 2009), Olaf always helped our class with sampling - he was always willing to get involved and stuck in, but jokingly teasing you the entire time for not being able to do things without him.

Poogendri Reddy Team building @ SAIAB in 2009. Olaf joined the team whole-heartedly and was always up for some fun.

Kerry-Ann Van der Walt On my masters field trip to Groot Marico, Olaf was constantly teasing me about my pink back pack, saying how small it was and does anything fit in it! He then proceeded to take the bag and put it on his back along with his net to make a point! This field trip was full of fun memories and the first trip I really got to know my masters supervisor Olaf! He was such a generous, intelligent, hard-working, soft-hearted man! He welcomed me into the SAIAB family and provided me with wonderful opportunities! I am forever greatful for this. He also inspired me in so many ways. I am extremeley saddened by his loss, and my thoughts and prayers are with his family during this difficult time. His big personality and legacy will always remain with us!

Darragh Woodford Olaf electrofishing for redfins in the Groot Uie River, Addo NP Kabouga Section. I was brought into Olaf's research group at the the beginning of 2011, and spent the next four years as a member of a team of post-docs that greatly advanced the state of knowledge of freshwater fish invasion biology in South Africa, including their spread, impact and control. Olaf was relentless in his pursuit of research excellence and pushed us, his tea,m to aspire to the same levels, so that we could become competitive on the global stage of fish biology and ecology. My PhD had previously taught me how to think like an ecologist, but Olaf taught me how to pursue a research problem in the most effective way to produce results, and to never rest on my laurels until that work was published. He was an inspiration to all of us, and kicked our post-doctoral careers into overdrive, for which we shall be eternally grateful.

Allison Luger

Allison Luger

Allison Luger Fishing trip with the 2013 research group

Michelle Jackson My fondest memories of South Africa involve Olaf. I arrived in June 2013, based in Gauteng, but with a fishy project in mind I had been in contact with Olaf. Within days Olaf had booked me a flight to join his group at the annual SASAqS meeting in Arniston - he was always so generous, warm, and hospitable. Olaf was keen to show of the country he loved and took us on a trip to Cape Agulhas.

Leo Nagelkerke And another one from Bujumbura, where we all mysteriously lost our legs

Leo Nagelkerke After some visits to South Africa for a joint project I met Olaf again in Burundi (PAFFA conference). This is the fish market in Bujumbura, where Olaf and Bruce were much interested in what was for sale

Rowshyra Castaneda Olaf was a great and supportive supervisor. Here we are at CIB where Olaf was giving us a tour. Olaf was so generous with his time and knowledge. He is dearly missed.

Nick Mandrak Sundowner in Kruger NP

Nick Mandrak Field work in Ceres

Rowshyra Castaneda Olaf was such an amazing cook, making the most memorable field meals. Olaf made us delicious piri chicken on the braai during our fieldwork in Ceres.

Rowshyra Castaneda Olaf giving us the grand tour of a dam on a very stable and sufficiently sized rubber duck!

Dilermando Lima Among giants! I - a young researcher - talking to Kirk Winemiller, Julian Olden, Jean Vitule, Emili Garcia-Berthou and Olaf Weyl.

Julian D. Olden Wonderful adventures with Olaf in Recife, Brazil. Pictured with Jean Vitule and Kirk Winemiller.

Julian D. Olden Great times with Olaf and Jean Vitule in Recife, Brazil.

James Vonesh I first met Olaf duing a grant writing retreat at Crown River Safari Lodge in 2015. Olaf and his lab toured us around their river, canal, and pond study sites around the Sundays River. Olaf's generous nature, knowledge and enthusiasm were infectious. He made me feel like an old friend even though we had only met.

Michelle Jackson During my 3 years in South Africa Olaf was the common theme in all of my research – he invited me along on field trips, got me involved in new projects, and was instrumental in finding field sites for my own CIB funded postdoc. I will always be grateful for all of the opportunities he gave me. Some favourite memories are from a trip to Namibia with Olaf, Jackie, Gerry, and Rich, in which Olaf teasingly named me the ‘field work saboteur’ – making light of situations including me leaving my passport on the other side of the country and dropping some gear in the delta!

James Vonesh After the ZSSA meetings in 2015 Olaf invited my family to join his for a couple days at Hogsback. Our daughters are of similar age and we wanted our families to get to know each other. That week was a time of crisis for my family, as we were learning that our youngest had leukemia. We suspected something was terribly wrong but didn't know what and we couldnt help imagining the worst. It was almost a relief when we learned what she had because then we knew what we were up against. During this difficult time Olaf and Michelle were incredibly supportive. Although our families only spent a handful of days together - their story is forever interwoven with ours.

Darragh Woodford At the 2015 SASSAqS annual conference, both Olaf and myself were presented awards for our services to the society, having attended the meeting uninterrupted for 5 years while both having a change in career status. Olaf had just been made full professor at Rhodes University, while I had been hired as a lecturer at Wits University. This was in many ways the culmination of our professional relationship over the previous 4 years, with Olaf receiving the recognition for his astonishing research output, and me reaping the reward for having been a part of that research journey with him.

Jean Vitule At ground zero of the invasions of Africa, as Olaf said. Great invasion scientist!

Jean Vitule I love you my brother in fish!

Jean Vitule CIB with Davi Richardson! Nice days! Thank you so much Olaf!

Jean Vitule Cape Town with Dr Mhairi Alexander, nice days, and nice food!

Jean Vitule With Dr Frehse in Morato River, very cold water, but Olaf´s love by fish was superior! Thank you my friend!

Jessica Glass Olaf filling the room with joy on Heritage Day 2015. Olaf never passed up the opportunity to pop into my office and share his thoughts about Donald Trump and the US presidency. He was able to laugh at the lunacy of it all and got me to laugh at it too. I think Olaf was more excited than I was about my new job in Alaska, since he knew he had a standing invitation to come salmon fishing. I'll catch a big one for you Olaf. You are greatly missed.

Tamara Robinson I only had the pleasure of Olafs company once a year. One of the things I looked forward to most about the CIB ARM was catching up on news of the girls in his life - Michelle, the twins and the dogs. He was stoic about being the only man in the house, but his eyes sparkled when he shared stories about being relegated to the girls beds and waking up with a Disney princess inches from his nose. One year he arrived and proudly gave me a book for my children. Written by Michelle in honour of the twins it soon became a firm fav in our house! I'll always remember Olaf has a wonderful, smart, kind, inspiring person who loved his family dearly.

André Magalhães Good times!! Limnology Meeting 2016, city of Curitiba, State of Paraná, Brazil.

John Hargrove Saying farewell to our host Pete Marriot at the Casa Msika on Lake Chicamba. Olaf, Neil Deacon and I arrived with visions of landing 10 lb bass on every cast, and left feeling grateful to have 50 genetic samples from whatever bass would bite. Always eager to understand patterns, Olaf would later find out that we should have been fishing along the gill nets set by locals in mokoros and that when they banged paddles on the water those were dinner bells for hungry bass

John Hargrove Truly a legendary angler, Olaf schooled me on the ways of catching tilapia in Okavango Delta. Just one of many unforgettable fishing adventures

Jean Vitule In SELCS 2016 in UFPR BR with Dan Simberloff.

Jean Vitule Guaraqueçaba, Salto Morato reserve - BR

Jean Vitule So many good memories! Thank you! Botanical Garden, Curitiba, Parana, Brazil.

Jean Vitule Guaraguaçu River, Atlantic Rain Forest, BRAZIL

Marliese Truter My first real fieldtrip with Olaf. Dumi you were brave on that trip, even warned me about that mischievous and amusing grin Olaf gets when a ton of work is about to rain down on you. I will forever cherish that.

Dumisani Khosa Fishing at Groenvlei

John Hargrove A guided saltwater fishing trip following the 2017 AFS meeting in Tampa with Mike Allen. Ever keen to expand his species list - Olaf tacked on several new catches to his list this day

Fabricio Frehse Thanks Olaf for all your support and shared moments and knowledge.

Becky Cudmore So many wonderful memories of an equally wonderful person. It’s obvious from this page that Olaf had a genuine quality about him that drew people to him. I enjoyed all our quiet conversation, boisterous stories and all our outdoor adventures. Olaf was dear friend; I will miss him greatly.

Ross Cuthbert Olaf visits QUB in N Ireland. Shortly after, Olaf warmly hosted me in his lab for six months (then another six months) where he generously supported our work in ephemeral ponds ("puddles", as Olaf called them), laying the groundwork for collaboration. Stellar scientist, friend and family man.

Nick Mandrak

Nick Mandrak Always the proud Mentor!

Dumisani Khosa From sampling Florida Bass in Stutterheim

Dumisani Khosa End of the year function with the research group

Maz Wong Without having even met me before, Olaf hosted my sabbatical in South Africa and invited me to come along on one of his Cederberg trips to experience his research first-hand. I instantly felt so welcome by him, his family and his group. Even the long car ride from Grahamstown to the Cederberg didn't feel so long sitting next to Olaf, who chatted away about anything and everything, revealing just how intelligent, kind and funny a person he was. I think he delighted in my fondness for biltong and ensured that I had sufficient supplies at all times. On one of the nights we had a good old S African braai too and there were always plenty of gin n tonics to go round! So many good memories thanks to Olaf.

Jean Vitule Olafinho my brother was not only an outstanding research colleague but also a good friend, a bigger brother to me. We fished and travelled together in Brazil and South Africa many times. He was taken from our lives suddenly, by surprise, and not too long ago he mentioned to me he would like to be fishing when this happened. I will always remember him laughing and fishing, and will miss him immensely. Olaf loves fish and good people...

John Measey Olaf communing with the fishes. Never happier than when hanging out with the fishes... or teaching others how to hang out with the fishes.

Fernandu Harold Khaebeb Cederberg Excursion: The gentle giant with golden a heart, faith and ability to see potential in all, regardless of who or where you from. Am grateful, I met the angel Olaf, thank you for your teachings and guidance, I am forever grateful.

Lucky Brian Dlamini My first memory/interaction with Olaf was in April of 2018 when I was an NRF intern and he took me on my first field trip to Addo Elephant National Park to provide media coverage for his World Fish Migration Day event, with the rangers from the Park. To end off the day we had a very fulfilling skottel braai prepared by Olaf – one of the best that I’ve ever had! 🙂🙂 (You can read the short report I wrote after that trip here: https://www.saiab.ac.za/newsroom/celebrating-world-fish-migration-day.htm ) Photo cred: Olaf Rest in power 🙌🏽

Nick Mandrak On a hike with the Weyl family.

Josie South Fish Supper 2018. Wearing Olafs blazer because it was longer than my dress. Laughing at Olaf for being a scruff and never tucking his shirt in. Olaf still laughing at Taku eating oysters.

Casey Broom Olaf overseeing our fish handling certification training

Casey Broom Team lunch at Rustic Route

Josie Pegg

Thiago Occhi Professor Olaf give me some tips on how to regulate the engine to a better performance in wavy sea. One of the many things I learned from him

Marcelo Brito Non-native fish symposium, XXIII Brazilian Meeting of Ichthyology, city of Belém, state of Pará, Brazil

Marcelo Brito Olaf's presentation at the XXIII Brazilian Meeting of Ichthyology, city of Belém, state of Pará, Brazil.

Jean Vitule Fishing in Belém. In estuaries. Good friend the best fisherman that I knew.

Jean Vitule Snooks Centropomus paralellus and C. undecimalis in São Caetano de Odivelas. Niche fishing. Nice trip. We tried açaí but we preferred fish, beer and cachaça.

Jean Vitule Goliath grouper baby. In the river.

Jean Vitule Mercado Ver o Peixe, Belém do Pará BR.

Josie South Collecting The Esteemed Professor Vile from the airport at Kasane. He got off the plane and announced “By the way, I have gout. South do you have any cigarettes? I’m considering starting again”

Josie South Olaf presenting at SANBIs invasion symposium. This particular morning was the one where he was so hungover couldn’t quite form words properly. I got the blame for that, and some inherent respect aswell

Josie South Olaf putting up his mosquito net tent, on a sand island next to Popa Falls in the middle of the Kavango River.

Ryan Wasserman Olaf meets Harrison. One of my fondest memories.

John Measey Olaf with some slightly mischievous intent. We once showered together... https://youtu.be/Ml3wzGnvq8w (follow this link at your own risk)

Josie South SAIAB 50th Birthday, Olaf and mini Olaf. We kept the laminated face pinned up in our office afterwards

Josie South Olaf and I in our natural state (sulking). Olaf is sulking because he “hates Angus’s kumbayah meeting”, I am sulking because Angus made me put shoes on. Denis is taking the sneaky pictures

Allison Luger Open letter by Allison Luger

Marliese Truter

Casey Broom An open letter for our friend Olaf

SAIAB NRF-SAIAB Olaf's research group

Josie South An open letter for my friend. We miss you Olafinho.

Rob Britton Olaf fly-fishing for yellow fish on (I think) the Orange River. I rarely saw him more content than when he was fishing, especially fly-fishing.

Rob Britton Olaf’s hospitality at his cottage Cannon Rocks was great and I will never forget it. On this day, he gave me his fishing rod and sent me to the beach to catch us dinner. Having managed to catch us some fish, he cooked them on the braai. His subsequent - and unintentional - put-down still makes me laugh now, it was something like ‘You know, these fish are really good, I’m so glad you caught them for us to try, as I don’t normally catch ones this small’.

Nicholas James Loskop Dam January 2020, with Angus, Mandla and myself Nick James, during our first Mpumalanga Tilapia survey. All the day's work was done...just crossing the dam to relax.

Nick Mandrak Cheers to my dear friend!

Jean Vitule 5 a.m. fishing

Jean Vitule We and our friends! Fish! We love fish!

Jean Vitule Bother in fish!

Pedro Bragança Saudades Olaf! Everybody smiling, happy, having fun.... That's Olaf's magic! I will never forget it, and it is still with us..... You only need to meet Olaf's pupils. Obrigado Olafinho!

Josie South Southern Hemisphere invasion science workshop. We foraged oysters and made caipirinha. Olaf made squid on the braai and laughed at Taku eating oysters

Hien Ngo We were fortunate enough (the entire team) to meet and work with Olaf in March of this year. After many hours over many months this year we all got to know Olaf well. Even through the screen I could tell what a kind and lovely person Olaf was - your big bellowing laugh will forever be burned into my memory. We will continue to celebrate your life forever.

Rob Britton Being UK based, a lot of my contact with Olaf was by messages and video, and whilst we always intended to discuss work, we would mainly talk about fishing, such was his - and my - passion for it. His fishing stories always trumped mine, especially the big bass were biting!

SAIAB NRF-SAIAB "After speaking to a few colleagues at SANParks it became clear just how much of an influence Olaf had within the organisation. As such we would like to convey our sincere condolences to you, to SAIAB, his colleagues, friends and family. We have tried to encapsulate a little of what Olaf meant to those of us in SANParks with whom he interacted in the attached letter." Kyle Marine Ecologist South African National Parks Rondevlei Scientific Services 044 343 1302

Francesca Porri Two unrelated images to remember you Olaf (I should have added the one about some bubble wrap I used to leave for you as antistress!). The one about you going out in all ways to coordinate, inspire,motivate, nurture the scientist body at SAIAB. This was a selfie of us all during our scientist retreat, because to do well and the best for the institute and the students,we needed a focused getaway...and a beautiful fish braai! I still remember you came to ask me what you could cater for an Italian gone vegan!😜 The second photo is of today in the field. I was battling to get going on the weekend and almost postponed. I knew what was right and Gavin and Angus persuaded me that Olaf would have wanted the field 100%. So here i dedicate to you this coastal pacifying sampling with Paula,under a gentle rain and a blessing ritual by a Khoisan chief. Go well Olaf...I will miss a mischievious and loud buddy at SAIAB❣

Josie Pegg Some current Weyl Lab students and postdocs at the gates of SAIAB. We’ve lost the best supervisor but are very grateful that we did have the privilege of his mentorship for the time we did.

Jax Hill Field trips with Olaf were always an adventure, from replacing bearings in a boat trailer by flashlight in the backend of Katima-Mulilo, to fishing for tigerfish at dusk, after a full day of fishing for science. Gin and tonics on the river, braais in the vlei and, above all, laughter. Grahamstown memories are equally warm, with dinners with Michelle and the girls involving gourmet food, stories and friendship. He was larger than life in his ability to love, he helped me pick up the pieces of my life when we lost Sven and he had this uncanny ability of making everyone feel special. What has become obvious over these past days are the myriad ways in which he touched the hearts of so many people all over the world. He has forever changed the way we view science, ecology, fisheries and friendship. You are already fiercely missed. Go well my friend, you are loved.